PHOENIX -- Chad Billingsley's strained right groin improved enough Friday that he extended a brief bullpen session into a normal one.

"I started slow, but it felt fine and it turned into a regular bullpen," said Billingsley, who felt a twinge in Monday's game against the Angels. "I made 30 pitches, and it went well. I threw everything."

Billingsley said he expects to throw a simulated game on the Minor League side Sunday instead of taking his normal start for the Dodgers against the White Sox. He also said he expects to be ready for the regular season. Billingsley's first start would be in the club's third game in San Diego on April 8.

"The past few days, I could tell playing long toss that I wasn't too worried about it," Billingsley said. "On the mound it felt normal. It wasn't game effort, but it felt like a normal bullpen."

While Billingsley downplayed the seriousness of his injury, manager Joe Torre insisted the club will exercise caution with Billingsley, who suffered a similar injury earlier last spring that Torre felt contributed to Billingsley's rocky spring and April.

"I'm still concerned," Torre said before Billingsley's bullpen session. "You don't really know until they get into a game."

Billingsley said he also had a bad groin strain in 2004. He said the treatment and recovery schedule for this one is patterned after the one last spring, which is why he is throwing in a simulated game Sunday and not the regular game.

"I'll still try to get to 90 pitches," Billingsley said. "It will just be monitored."

In other pitching news, right-hander Claudio Vargas said his elbow was too sore to play catch, which essentially takes him out of the competition for the fifth-starter spot. Vargas said he might need as many as two weeks off to calm the inflammation.

That leaves three main contenders for fifth-starter role, with rookie James McDonald the apparent front-runner ahead of Eric Milton and Eric Stults. Torre said that 21-year-old Josh Lindblom, who is throwing an increasing number of innings, will stay with the club at least through the final exhibition games in California.

Lindblom hasn't been ruled out for an Opening Day staff spot.