6 Biggest X-factors for Dallas Mavericks heading into Finals

4. Dereck Lively II

Dallas Mavericks rookie big man Dereck Lively II has been amazing in his first playoffs, and now he'll face his biggest test yet against the Boston Celtics. Lively II has had many tests through the first three rounds of the playoffs as he's faced Ivica Zubac, Chet Holmgren, Karl-Anthony Towns, and Rudy Gobert, and now he'll face two more elite big men.

The Celtics' bigs, Kristaps Porzingis and Al Horford, both stretch the floor, and Lively II will be prepared to guard both of them when needed. Lively II has grown a ton as a defender in space this season, and playing against Holmgren in the second round will help prepare him for this matchup.

The last time Dallas played Boston, threes from their bigs killed the Mavs. Horford and Porzingis were bombing threes in that game, and Lively II has to be sound when moving his feet on the perimeter.

Lively II is averaging 8.6 points, 7.2 rebounds, and 1.2 blocks per game in these playoffs, and his play on both ends of the floor could make or break this series. He will likely continue to be a big difference-maker in the pick and roll due to his screen setting and lob-catching ability, and he will have his work cut out for him.

Guarding Horford and possibly Porzingis won't be an easy task, but Lively II is cut for the challenge and has shown why he deserved to be on the All-Rookie First Team. He has been great all playoffs long, and he continues to exceed everyone's expectations.