KANSAS CITY, Mo. -- The Kansas City Chiefs and wide receiver Rashee Rice have "a lot of optimism'' that his knee injury isn't as significant as initially feared and that his recovery timeline could be "much shorter'' than first believed, a source told ESPN's Adam Schefter on Monday

It's still unlikely Rice will play again this season, but doctors will not know for sure until they perform surgery Tuesday morning, the source said.

Rice injured his right knee in the Chiefs' Week 4 win over the Los Angeles Chargers. Sources initially said Rice was feared to have torn his ACL, but the team has yet to officially clarify the nature of the injury. There is damage to the lateral collateral ligament (LCL) in his knee, a source told Schefter.

The Chiefs placed Rice on injured reserve Thursday in a move that will sideline him for at least the next four games.

Rice was injured when quarterback Patrick Mahomes accidentally collided with his knee when the two and other players were chasing a Chargers fumble that followed an interception.

Rice entered Week 4 leading the NFL in receptions with 24 and was second in yards with 288.