The Los Angeles Angels will send Chase Silseth to the mound to make his major league debut Friday night against the host Oakland A's in the opener of a four-game series.

The Angels needed an extra starter because of a Saturday doubleheader, and they elected to promote Silseth from Double-A RocketCity after the right-hander went 2-0 with a 1.73 ERA in five starts for the Trash Pandas.

Silseth, 21, was an 11th-round selection in 2021 as part a draft in which the Angels drafted all pitchers. The University of Arizona product will be the first player drafted in 2021 to reach the big leagues in all of baseball.

He pitched well for Rocket City, which plays in Madison, Ala., giving up two runs or fewer in all five starts and striking out 37 in 26 innings. He was selected the Southern League's pitcher of the month for April.

Silseth lasted six innings in each of his past three starts, but the Angels will have a bullpen rested and ready thanks to an off day on Thursday.

Anchored by closer Raisel Iglesias, the Angels' bullpen has been solid. The relief corps, which currently also includes Aaron Loup, Jimmy Herget, Oliver Ortega, Ryan Tepera, Mike Mayers and Jaime Barria, has an 8-3 record and a 3.49 ERA.

"The bullpen is used more in today's game, and I've always said that you have to be able to use everybody," Loup said. "If you don't have the confidence to throw, say, your lowest guy on the totem pole in a big situation, then we're not going to be any good."

Angles manager Joe Maddon feels comfortable no matter which reliever he brings into the game.

"Putting guys in different situations is always about trust," Maddon said. "The more people that gain your trust, the better chance you have of staying strong all year."

Right-hander Daulton Jefferies (1-5, 5.22 ERA) starts Friday for Oakland. He lost each of his past five starts after winning his initial outing of the season.

"I've gotta learn from the good performances and the bad ones," Jefferies said. "I try to take positives from every outing. ... I'm just trying to learn through every outing and make consistent starts for the ballclub."

In his most recent outing, Jefferies gave up four runs on seven hits in five innings during the Athletics' 4-3 road loss to the Minnesota Twins on Sunday. He struck out three without issuing a walk.

Jefferies, 26, has faced the Angels just once in his career, earning a win on Aug. 1, 2021, after throwing five innings of three-run ball.

The A's have won four of their last five following a nine-game skid. They have prevailed in each of their past three games, outscoring the host Detroit Tigers 18-4 in those contests, including a 5-3 win on Thursday.

"I think there was a focus here over the last few days to be more selective," A's manager Mark Kotsay said of his hitters. "They worked counts, they focused their approach to take what was given to them, and I think they did a great job with understanding what was needed."