San Diego Padres reliever Yuki Matsui will not pitch for Japan in next month's World Baseball Classic due to a groin injury.

The 30-year-old left-hander was ruled out Thursday, about a week after experiencing tightness in his left groin in a batting practice session at spring training.

"It's pretty disappointing," Matsui said through team interpreter Ike Ogata. "Especially since I didn't do so well in the last WBC, and I was looking forward to playing in this one. But that's not the only thing. It's baseball. I'm trying to move on, to get the best preparation for the season and to play for the Padres."

Matsui went 3-1 with a 3.98 ERA in 61 relief appearances for the Padres last season. Overall, he is 7-3 with a 3.86 ERA in 125 appearances for San Diego but has served up 18 homers in 126 innings over two seasons.

Matsui's status still is up in the air for San Diego's regular-season opener against the visiting Detroit Tigers on March 26.

"Right now, I'm just continuing the throwing progression, getting intensities and distances of (playing) catch back up," Matsui said. "Once it's good enough, then I'll start throwing off the mound. But as to when, we don't know yet. ... We're not sure yet (about Opening Day)."

Defending champion Japan's first game in the WBC is March 6 against Chinese Taipei.

Matsui was replaced on the roster by fellow southpaw Yumeto Kanemaru, who pitches for the Chunichi Dragons in Japan.