For the fifth time in six seasons, the Philadelphia 76ers once again entered the NBA playoffs with championship hopes and are potentially seeing their plans derailed by an injury to Joel Embiid.

The MVP frontrunner suffered a sprained knee in the Sixers’ first-round win over the Brooklyn Nets and is likely to miss Game 1 of the Eastern Conference semifinals against the Boston Celtics.

“This is the series that we’ve all been waiting for all year,” forward P.J. Tucker said, per Keith Pompey of the Philadelphia Inquirer. “And for us to not know if he’s gonna to play, yeah, that sucks because we’ve run everything through him.

“So it’s almost like we have to figure out another way to play because the way we [want to] play, we are not going to be able to play.”

Embiid is currently considered doubtful for Game 1 in Boston, and there has been no formal timetable set for his return.

The Celtics vs. 76ers series was, at least on paper, perhaps the best potential matchup of the second round—particularly after the Milwaukee Bucks’ first-round upset loss to the Miami Heat. The winner of this series will be a significant favorite going into the Eastern Conference Finals, and losing Embiid takes away much of the intrigue.

Boston is currently listed as a massive -560 favorite to advance at FanDuel Sportsbook.