TEMPE, Ariz. -- Left-hander Dillon Peters will start the Cactus League opener for the Angels against the Giants on Saturday at Tempe Diablo Stadium at 12:10 p.m. PT.

Peters, acquired via trade from the Marlins in November, is competing for the fifth spot in the rotation with right-handers Jaime Barria and Felix Pena. He’ll be throwing roughly 30 pitches with the goal of getting through two innings.

“He’s been good and he’s been working on some stuff,” manager Brad Ausmus said. “But I wouldn’t read too much into who is starting the opening day of Spring Training. It’s a matter of the schedule and who is available and needs the innings. We’re getting to the point now where performance factors come into play but certainly we won’t weigh performance too much early.”

Peters, 26, has pitched parts of two seasons with the Marlins, posting a 6.10 ERA with 44 strikeouts, 34 walks and seven homers allowed in 59 innings. He has a fastball that averages roughly 91 mph to go with a curveball and changeup. He has a career 3.37 ERA with 285 strikeouts, 79 walks and 22 homers allowed in 339 1/3 innings in four seasons in the Minors.

He said he’s been working with new pitching coach Doug White to improve his spin rate on his four-seam fastball, utilizing the new tracking devices in camp such as the Rapsodo, Trackman and Edgertronic high-speed cameras.

“The numbers show if you throw a fastball with better spin you have a better chance of succeeding,” Peters said. “So obviously I’m going to listen to that. It’s a factual, analytical number. It’s grip-related and I’ve been doing various drills to stay behind the baseball for as long as you can.”

Ausmus said the Angels don’t plan to roll out too many regulars in the first game because of their schedule in the coming days.

“There will be a few regular players, but not all of them,” Ausmus said. “Keep in mind we have a split squad the second day, so you have to take that into account.”

Rain moves practice indoors

The rain on Thursday forced the Angels to move their workouts inside, including their live bullpen sessions in the cages. But hitters weren’t allowed to swing because of safety reasons and instead tracked pitches.

With more rain in the forecast Friday, the Angels are postponing their workouts by an hour. Ausmus said the main issue is they aren’t able to do some of the on-field drills they had scheduled, but said it’s so early in camp they’ll find time to reschedule those drills.

Angels tidbits

• Shohei Ohtani took more dry swings on Thursday and is nearing hitting off a tee, Ausmus said. Ohtani, who is recovering from Tommy John surgery, said Wednesday he’s getting close to that next step.

• Right fielder Justin Upton, who is dealing with right knee tendinitis, won’t be ready for the start of Cactus League play, but is continuing to make progress, hitting off a tee and taking soft toss before he moves up to taking batting practice.