Hideki Matsui was placed on the 15-day disabled list Friday with a sore left knee, leaving the New York Yankees without one of their key sluggers.

The team also optioned reliever Ross Ohlendorf to Triple-A Scranton/Wilkes-Barre and recalled left-hander Kei Igawa from its top farm club.

Matsui missed the Yankees’ 15-6 loss to the New York Mets in the opener of a rare two-stadium Subway Series doubleheader. He hit in the batting cage and ran in the outfield before the game, but the Yankees opted to place him on the DL, retroactive to Monday, after the loss.

Manager Joe Girardi said he hopes Matsui’s balky knee won’t keep him out longer than a couple of weeks.

“I hope it settles down,” Girardi said.

Matsui had right knee surgery during the offseason, but it’s his left knee that is hurting. He is batting .323 with seven homers and 34 RBIs in 69 games.

The Yankees purchased right-hander Sidney Ponson’s contract from Triple-A and started him in the second game against the Mets.

Ohlendorf struggled with his command and was roughed up in the opener. He gave up a grand slam to Carlos Delgado and was charged with six runs and five hits in 1 1-3 innings. He is 1-1 with a 6.53 ERA in 25 appearances.

The Yankees spent $46 million to bring Igawa over from Japan before last season, but he has been a major bust. After going 2-3 with a 6.25 ERA for the Yankees last year, he made one start for them this season and was tagged by Detroit for six runs and 11 hits in three innings on May 9.