After the dismantling that Boston did to the drama-filled Brooklyn Nets in the first round, the Celtics turn their eyes to the next challenge in their mission for immortality. Milwaukee cruised past the struggling Chicago Bulls in five quick games where the majority of them were blowout wins. In Game 2, Bucks' All-Star Khris Middleton sprained his MCL and is expected to miss a minimum of two weeks of competitive action. Middleton is a known Celtic killer over the years. He has completely torched Boston including netting a near triple-double in the teams' last meeting in this year's regular season. These two teams split the season series with the Celtics taking the first two games, and Milwaukee securing the last two victories. It is going to be a battle of arguably the two best teams in the Eastern Conference as both teams had a top-10 defense in the regular season. Both squads are well-coached, share the basketball, spread the floor, and have one player that makes it all move in the right direction. If Boston wants to make its first Finals appearance since 2010, it is going to have to get through the Bucks either way. This series will be filled with plenty of excitement, physicality, and jaw-dropping moments, here are five things to look for ahead of Sunday:

1. Giannis against the physicality of the Boston defense:

Heading into this star-studded showdown, the two-time MVP knows he is going to be faced with far more resistance than he did against the Bulls in the first round. Against Chicago in round one, Giannis Antetokounmpo averaged 28.6 points per game to go along with 13.4 rebounds and 6.2 assists. Boston was able to limit Durant to under 39% from the field using multiple guys including Grant Williams, and Jayson Tatum who were fearless in pursuit to stop one of the greatest scorers of this generation. The Celtics made Durant more uncomfortable than he has ever felt in a playoff series. The versatility to have five guys that can guard almost any position with confidence makes Boston such a dangerous team to matchup against.

Boston does not shy away from contact, and physical play, but Giannis does not either. Something is going to have to give. Players like Grayson Allen, Massachusetts native Pat Connaughton, and Wesley Matthews will be called upon a plethora of times on the perimeter to make a play when Giannis just simply cannot power his way to the cup. Al Horford will spend most of the time on Antetokounmpo during this series, and the spread of the contests in this second-round matchup will give Horford a chance to recover. Durant is more of a jump shooter, while the best player in the next series is the opposite of a spot-up shooter. Boston's defense is going to have to funnel Giannis into the help defense in the paint. Just like against Durant, it is going to take more than one person to limit the impact that Antetokounmpo has in the scoring column.

Against the Nets, the Celtics' defense did not have the presence of Robert Williams III in the middle for a good portion of the series. He will be doing a lot of roaming during the second-round series against the Bucks. Horford should start on Brook Lopez while Williams III is best to be guarding a player like Portis or Matthews. When Tatum or Horford is staying in front of the two-time Finals MVP, they are going to need to body-check him without the ball. Turn Giannis into the jump shooter, force him into the help of Williams III and take a contested jumper from the elbow. Containing Giannis in this series is without a doubt going to be a priority, and if the Bucks want to head to the Eastern Conference Finals, players like Matthews and Connaughton will need to knock down their shots at a high clip.

2. Impact of Middleton's absence:

Against the Bulls, this was not a problem at all for the Bucks as other players like Grayson Allen, and Bobby Portis stepped up in their own unique ways. Whenever Middleton steps on the floor and sees the Celtic green on the other side, something inside him lights a fire in him. He continues to look like a man possessed against Boston in some of the biggest games, especially in the second round of the playoffs in 2019. Without him, Jrue Holiday is going to continue to be more aggressive in terms of taking it to the hole or creating his own shot. It is essentially just one less playmaker for Milwaukee, and against a Celtics team who is going to get after it on the defensive end, it could pose a problem. Allen is going to be essential when Giannis or Holiday simply cannot make a play due to the limited airspace they are given within the halfcourt offense.

As reported by Shams Charania, Middleton is expected to miss the entire second-round series against the Celtics. The recovery of a Grade 2 MCL sprain could see him missing the Eastern Conference Finals if the Bucks do make it past the Celtics. Middleton made it to his third All-Star team as he was just the second player on Milwaukee to average over 20 points per game. He is also the Bucks' third-best free-throw shooter on the team, and if the game is on the line, the number of quality shooters from the charity stripe will be limited.

Middleton showed out in the playoffs last season as he averaged 23.6 points per game, as well as dishing out 5.1 assists during the Bucks championship run. Losing the second-leading scorer on the team in a do-or-die situation against a team that is playing arguably the best basketball out of anyone in the league right now could prove catastrophic. In the regular season, the Bucks were 7-9 without Middleton, but none of that is important given the way the team played against the Bulls when he departed near the end of Game 2. Milwaukee recovered, and has that "next man up" mentality that Boston used when Williams III was sidelined for a few weeks. Allen has been terrific for the Bucks during the postseason, and with Middleton out, one of the most polarizing players in the NBA will have to knock down shots just like he did in the three blowout wins to close out the series against Chicago.

3. Trying to move up the food chain:

Tatum has now gotten past Kevin Durant and Kyrie Irving, but the man who still thinks that he is disrespected time and time again awaits with a repeat on his mind. Overall, Tatum is 5-7 in the postseason in his career in the playoffs against Antetokounmpo and has the chance to knock out two consecutive all-time greats in the same playoff run. Boston's path to the Finals this season may be one of the most difficult of anyone in the league. Tatum proved that he can outduel Durant in a seven-game series, but the question is if he can match up against Giannis and play the kind of elite defense he did Durant following a sweep that had four tightly contested games.

Tatum frustrated Durant with some of the worst shooting performances of his playoff career. The reason why Tatum worked in the weight room during the offseason is for playoff matchups like this one. Guarding Giannis is something that Tatum is going to be asked to do, but with his work in the weight room, he should be up for the challenge. Giannis is 27, and Tatum is only 24 years old. These two will be battling it out in the Eastern Conference for years to come. Both have out-of-this-world wingspans and the ability to take control of a game on both ends of the floor. Giannis is a certified complete two-way player, but Tatum is growing into that equation after his performance against the Nets.

Each player is the straw that stirs the drink for their respective teams. Giannis has come a long way from air balling free throws at the TD Garden. On the other hand, Tatum has evolved his game every season, improving in every facet of the game of basketball, especially this year. Beating Giannis in a playoff series the year after he won the championship puts Tatum into a different parameter of superstar. During his career, people have doubted Tatum and if people should call him a superstar, but a series win against the Bucks will squash that entire conversation and let the rest of the NBA know that Tatum has officially become the king of the Eastern Conference.

4. Second-chance points:

The one thing that Brooklyn had no answer for against the Celtics in the first round was their ability to get an extra possession in some of the most opportune times. Boston averaged 11 offensive rebounds per game in the Nets series, but the lack of confidence and quality in the paint for Brooklyn was a big reason why. Theis, and Williams III love to attack the offensive boards, and Portis, and Lopez have to be consistent when a shot goes up from the perimeter. The Bucks were the second-best rebounding team in the NBA in the regular season even without Lopez, so with him, Milwaukee could be the kryptonite to one of the things that won Boston its first-round series.

The Bucks still need to be watching for it as the Celtics are an elite offensive rebounding team, and punish the opposition for giving them another chance. Boston ranked 11th in offensive rebounds per game in the regular season while the Bucks were right behind it in 15th. Limiting the possessions for both teams and their stars is going to be one of the critical aspects that are going to decide the outcome of this series. Blocking out, and only giving Tatum and some of the Celtics' shooters one crack at an open look was something the Nets just simply could not do effectively.

Holiday possesses great vision and court awareness, and allowing him to attempt to break down Boston's defense more than once each time down the floor could result in a long game for Boston. Giannis averaged 11.6 rebounds per game in the regular season and has the ability to take over games with his length on the glass. As a team, the Celtics need to frustrate him with multiple bodies when a shot goes up. One of these teams' strengths is rebounding in general, but after watching Boston dominate the offensive boards and the paint against the Nets, the Bucks are tasked to remove that from the Celtics' winning formula.

5. Tactical coaching dual:

Two coaches that some would say were unfairly left out of the Coach of the Year finalist list. A coach that has been at the helm of an NBA team since 2013 will take on someone who is in his first year as a head coach following nine years as an assistant with three other teams. While the experience is on completely different spectrums, the quality and intelligence are arguably at the same level. Both coaches are defensive-minded and want their teams to get out and run in transition. The adjustments made by these coaches during the games, and between them are what is going to make this series somewhat of a chess match.

How are both coaches going to get their stars open against teams that pride themselves on limiting paint points? Udoka is going to have to get creative with some back screens and pick and rolls to get Tatum in the middle of the floor for him to be able to make an educated decision. What are going to be the matchups during this series? Last series, Boston attacked every mismatch that was made available. Fewer isolations and more ball movement are potentially going to be more of what each offense looks like. The mismatches are going to be few and far between, but there is no doubt that each coach is going to try their best to put their stars in the best positions to make the correct play.

Neither team was at their best during the regular season for any of the games. Boston was not at its best until the end of January while the Bucks missed one of their most salient players in Brook Lopez for essentially the entire regular season. Udoka is going to have to get Lopez out of the paint for Tatum and Smart to use their skills to get an easy basket at the rim. Which player on the Bucks or the Celtics is the opposing coach going to try to see if they can beat them? Ime Udoka against Mike Budenholzer, a coach that has been there as the head of a coaching staff against an upstart head coach who wants to prove himself each game. If Udoka can beat Budenhozer in a seven-game series, there is no question that he has arrived and can be known as not only the best first-year head coach but one of the best coaches in the league today.