The Toronto Raptors were already facing a 2-1 deficit in their Eastern Conference semifinal against the Philadelphia 76ers, but that deficit feels a whole lot larger with the prospect of losing forward Pascal Siakam for Game 4.

Adrian Wojnarowski of ESPN is reporting that Siakam is doubtful for Game 4 due to a right calf contusion:

If Siakam were to sit out tomorrow afternoon's contest in Philadelphia, the Raptors would be without their second-leading scoring (and, as Siakam has shown, their second-best player), putting a whole lot of pressure on Kawhi Leonard to maintain his torrid scoring pace.

Leonard and Siakam have been about the only positives for Toronto in this series. The two combined for 74 of the team's 108 points in the Raptors' lone victory during this series (Game 1), and Siakam has scored at least 20 points in each of the first three games.

Meanwhile, Leonard is averaging over 36 points per game for the Raptors as his teammates have struggled to pick up the slack. Without Siakam in the rotation, it would likely take another Herculean effort from Leonard to pull out a win in Philadelphia and even the series.

There is no question that the Raptors simply need more from point guard Kyle Lowry. The 32-year-old All-Star has been anything but for Toronto so far, averaging just 12 points and shooting around 35 percent (including a 2 of 10 performance in Game 3) so far.

Aside from losing Siakam, the Raptors will also have to contend with a healthy-looking and rejuvenated Joel Embiid, who torched Toronto for 33 points, 10 rebounds and five blocks in Game 3.

Needless to say, the Raptors face an uphill climb in their quest to draw even with Philly.