Matsui had been held out of New York's lineup for a second successive game as the Yankees dropped a 10-3 decision to the Mariners on Sunday. The 35-year-old has battled chronic knee issues all season, but he has not required draining since the club's first homestand in April.
"Personally, I'm not worried, as long as we do the same kind of treatment as we did in April," Matsui said through an interpreter. "I'm not that concerned."
Yankees manager Joe Girardi said that he had planned to rest Matsui anyway for the series finale against the Mariners due to stiffness in the left knee.
Girardi was told by head trainer Gene Monahan that Matsui needed another day, and after having the draining performed, the manager suggested that Matsui would rest on Monday and could appear as early as Tuesday, when the Yankees play the second game of a three-game set against the Athletics.
"It's the first time in a long time," Girardi said. "Is it a concern of mine? A little bit. Hopefully we get it out."
Batting .266 with 19 home runs and 58 RBIs in 104 games, Matsui said that his left knee had started to swell up "four or five days ago." He homered twice in a four-hit, five-RBI game for New York on Thursday, and he has 12 hits in his past 36 at-bats.
With Matsui on the bench, Mark Teixeira started as the Yankees' designated hitter and Nick Swisher manned first base.
Matsui had arthroscopic surgery on his left knee in late September last season, missing the Yankees' final road trip of the season. He also had an arthroscopic procedure performed on his right knee after the 2007 season.
Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.