ANAHEIM -- James Kaprielian will have to take a temporary respite from what has been a breakout rookie campaign for the A’s.

Kaprielian was part of a flurry of moves made by the A’s prior to Saturday’s game against the Angels. The right-hander, who has emerged as one of baseball’s top rookies this season by going 5-4 with a 3.24 ERA across 13 starts, was placed on the 10-day injured list with a right shoulder impingement.

“We’re hoping it’s not serious,” A’s manager Bob Melvin said of Kaprielian’s injury. “It’s inflammation in the AC joint of his shoulder. He felt it a little bit after his last start. We monitored it and it just makes some sense to, at least, skip him one turn in the rotation. This is a guy we want to keep healthy.”

Kaprielian was originally scheduled to start Sunday’s series finale. That start will now go to right-hander Daulton Jefferies, who will officially be added to the roster on Sunday.

Jefferies, the club's 2016 first-round pick who is ranked Oakland’s No. 4 prospect by MLB Pipeline, just narrowly missed out on making the Opening Day roster in what was a fierce three-man battle, along with left-handers Cole Irvin and A.J. Puk, for the A’s final rotation spot. Though he began the season in the Minors, he certainly left a strong impression on the big league staff with a stellar performance in the Cactus League. Over six games, the 25-year-old righty posted a 1.50 ERA with 24 strikeouts against just six walks in 18 innings.

In 12 starts with Triple-A Las Vegas this season, a majority of those coming at the ultra hitter-friendly Las Vegas Ballpark, Jefferies is 3-1 with a 5.19 ERA and 54 strikeouts against just nine walks in 59 innings pitched.

“It’s almost surprising that he hasn’t gotten a start here already,” Melvin said of Jefferies. “It’s just that our starters have been so durable and consistent. We knew he was next in line. He’s been pitching well and he’s been here before. This is why you create the depth you have, and it’s always nice to have someone come up that has been through your system.”