Padres left-hander Yuki Matsui experienced tightness in his left groin during a batting practice session on Thursday and is considered day to day, San Diego manager Craig Stammen said Friday.

Matsui had to halt the session after roughly 20 pitches and the club subsequently scratched him from his scheduled Sunday spring-training relief appearance against the Los Angeles Dodgers.

The issue also could affect whether Matsui can pitch for defending champion Japan in the upcoming World Baseball Classic.

"We've got to see how he comes out of this day off, and then how he feels (Saturday)," Stammen told reporters. "Honestly, I think it puts the WBC in question."

Japan's first game in the tournament is March 6 against Chinese Taipei. Stammen said the decision will probably be left to the 30-year-old Matsui, a reliever entering his third season with the Padres.

"He has got to make that decision," Stammen said. "He has got to be able to talk with the coaches and the (general manager of Team Japan) and see if that's still an option for him. It's going to be a tough road for him to get healthy enough to be ready to pitch in the WBC. But I'll let him address that. ...

"We've had internal conversations about it. Ultimately, it's up to him. We can't call Team Japan and say, ‘Hey, Yuki is not pitching.' Yuki has to make that decision, and I think he'll come to a pretty good decision on that."

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