LOS ANGELES — Dodgers right-hander Yoshinobu Yamamoto was placed on the 15-day injured list before Sunday’s game against the Kansas City Royals with tightness in the triceps of his pitching arm.

Manager Dave Roberts said Yamamoto, 25, would undergo testing Sunday to determine the severity of the injury and a recovery timeline.

“He’s a guy that we’re still trying to learn a lot about, and appreciate the fact that the most important time of the season is yet to come,” Roberts said. “His health is paramount. So for us to be proactive and put him on the IL seems like the smartest thing.”

Yamamoto, playing his first year in the majors after departing his native Japan and signing a record $325 million, 12-year contract, is 6-2 with a 2.92 ERA.

Yamamoto left Saturday’s loss to Kansas City after two innings. He said through an interpreter after the game that his scheduled start the previous Thursday against Texas had been pushed back because of the tightness.

He also said the tightness was gone for most of Saturday, but he started feeling it again when he was warming up before the game.

Yamamoto threw two-hit ball over seven innings at the New York Yankees on June 7. He tossed 106 pitches, the fourth straight time he had thrown more than 100.

Roberts said he has been mindful of Yamamoto’s pitch count, but also noted Yamamoto was used to throwing 120 pitches or more when he pitched in Japan.

With Bobby Miller returning to the rotation for Wednesday’s game at Colorado, the Dodgers will still have a five-man starting staff. Clayton Kershaw will also make his first rehab start this week.

Los Angeles’ rotation went into Sunday’s game with the majors’ seventh-lowest ERA at 3.49.

The Dodgers also placed right-hander Michael Grove on the IL with a right intercostal strain. Right-handers J.P. Feyereisen and Michael Petersen were called up from Triple-A Oklahoma City. To make room for Petersen on the 40-man roster, right-hander Joe Kelly was transferred to the 60-day IL.

LOS ANGELES — Dodgers shortstop Mookie Betts suffered a fracture in his left hand when he was hit by a 97.9 mph fastball from Dan Altavilla during the seventh inning of Sunday’s game against the Kansas City Royals.

The fracture, which is to a bone in Betts’ left wrist, will not require surgery, according to manager Dave Roberts. There is no timetable for his return, though he is expected to be out “for some time.”

“It’s a big blow. I feel bad for Mookie because he’s having an MVP-type season,” Roberts said.

The pitch hit Betts at the top of the hand, near the wrist. Betts fell to the ground and was writhing in extreme pain in the batter’s box as trainers and Roberts came out to tend to him.

Those watching on television and in the lower deck at Dodger Stadium could clearly hear the ball making contact with Betts’ hand.

Betts went 0-for-3 before exiting Sunday to drop his batting average to .304, ninth in the majors. He was fourth in on-base percentage (.405) and tied for fifth in hits (86).

Betts was asked what’s next for him.

“I’m honestly not sure,” he said. “Obviously, I’ll be watching the boys and cheering them on. Other than that, just kind of rest, maybe use it as a mental break and be ready to go whenever it heals up.”

Miguel Rojas is expected to see the majority of time at shortstop, according to Roberts.

The Dodgers, who defeated the Royals 3-0, head to Colorado for a three-game series starting Monday.

The Associated Press contributed to this report.

BOSTON — New York Yankees top prospect Jasson Dominguez was placed on Triple-A Scranton/Wilkes-Barre’s injured list Sunday with a left side injury.

Yankees manager Aaron Boone said Dominguez suffered the injury on an “awkward” checked swing in his third plate appearance Saturday. He finished the at-bat, striking out looking, and played another inning in center field before he was removed from the game. He went 1-for-3 with a stolen base and two strikeouts.

“He’s getting testing today,” Boone said before the Yankees faced the Boston Red Sox on Sunday. “But it’s enough to put him on the IL right away at least. I’m sure we’ll have an idea — hopefully have an idea — with what exactly we got by tonight or [Monday].”

One of the more heralded prospects in recent years, Dominguez, nicknamed “The Martian,” made his major league debut last September before his 21st birthday. He played in eight games for the Yankees, batting .258 with four home runs, before tests revealed a torn ulnar collateral ligament in his right elbow. He returned to the field after surgery in mid-May on rehab assignment.

The rehab assignment ended Wednesday when the Yankees, who have a surplus of outfielders, activated Dominguez from the 60-day injured list and optioned him to Scranton/Wilkes-Barre. Dominguez slashed .389/.405/.609 in nine games in Triple-A before the injury.

Dominguez was in the outfield for Gerrit Cole‘s dominant rehab start Friday for Scranton/Wilkes-Barre. The question now is whether Cole’s next outing will be his season debut in New York this week.

The Yankees are choosing between having Cole and Cody Poteet start Wednesday against the Baltimore Orioles at Yankee Stadium. The team has “TBA” listed for now.

“I think we’re just going to get through today and probably make it tonight or certainly [Monday],” Boone said.

Cole, 33, has made three rehab starts since returning to game action after being diagnosed with nerve irritation and edema in his right elbow in mid-March. On Friday, the reigning AL Cy Young Award winner held the Rochester Red Wings to one unearned run on two hits over 4⅓ innings. He struck out 10, walked none and threw 68 pitches. In all, he has given up two runs (one earned) across 12⅓ innings in his rehab showings.

“We don’t have to make that final call right now,” Boone said. “He’s going to pitch, probably in that five- or six-day window coming off his last one. Let’s just not tie ourselves to something until really we have to.”