New York Knicks sixth man J.R. Smith played in the postseason with fluid in his left knee, a league source confirmed to ESPN. It is unknown at this time whether Smith will need to undergo a procedure to drain fluid from his knee at this point, the source said.

A second source close to the player said the guard started complaining about knee pain during the Knicks' opening series against Boston. However, Smith did not mention the injury or any knee pain publicly during the postseason or use it as an excuse for his poor play.

Smith accepted the blame for the Knicks' Game 4 loss due to his poor shooting performance. The injury appears to have impacted the 2012-13 sixth man of the year's shooting.

Smith averaged 22 points on 48 percent shooting in the final month of the regular season but struggled with his shot in the playoffs. He averaged 14.3 points on 33 percent shooting in a disappointing postseason.

Smith first suffered knee pain and swelling in early March. According to a source, it flared up again in the playoffs.

The New York Post, which earlier reported the injury, reports that Smith likely will have his knee drained in the next two weeks.

Smith began the first the games of the postseason with a strong start, averaging 16.3 points on 43.5 percent shooting. But Smith was suspended for Game 4 of the Knicks-Celtics series for elbowing Jason Terry in the face, then his play suffered. Smith scored 13.5 on 29 percent shooting in the eight games after the suspension.

Smith is expected to test free agency this summer, and his postseason struggles may impact his market value. New York has Smith's early Bird rights and can offer him a four-year contract starting at approximately $5 million with standard raises. Another team with significant cap space can offer Smith more than $5 million annually.