Most eyes will be on Joel Embiid.
Al Horford will also be a favorite target for those watching Monday night.
Then there will be those worrying about Tobias Harris.
But here's the thing Celtics fans: You should start getting to know a rookie by the name of Matisse Thybulle.
When the Celtics take on the Sixers Monday night to kick off their best-of-seven series in Lake Buena Vista, Fla. it is this guy -- the 20th overall pick in last year's NBA Draft -- that could play a key role in whether or not the C's are able to advance. (Philly actually traded with the Celtics in the Draft to move up to select Thybulle.)
So why is this player so important? This is a 23-year-old who averaged just over four points per game during the regular season and even less in the bubble play-in games. In the four games against the Celtics, the 6-foot-5 Thybulle totaled 23.5 minutes per game, serving as an afterthought while Philadelphia was taking three of the teams' four meetings.
But now he is important. In fact, Thybulle may very well be in the Sixers' starting lineup.
It was the Sixers' ability to limit Tatum that went a long way in getting the better of Boston during those three wins. Except that was with Ben Simmons, who guarded the Celtics start in 155 of the 250 half-court possessions, according to Second Spectrum's player tracking data. The matchup resulted in a subpar Tatum, with his numbers jumping up in the 95 possessions Simmons wasn't on him while shooting just 33 percent from the floor in the four games.
Simmons, of course, won't be around this series due to knee surgery. That's where Thybulle comes in.
"I mean, it's just really no different," said Thybulle, who has been assigned to Kemba Walker primarily in the previous meetings. "Every game I've played, essentially, my job has been to guard the best player, maybe with the exception of like Kawhi (Leonard) and LeBron (James). But, so really for me, this is no different.