Starting pitcher James Paxton limps off the field with the help of Manager Alex Cora, left, and a trainer in the first inning of the Red Sox’s 10-2 loss to the Astros on Sunday at Fenway Park in Boston. Michael Dwyer/Associated Press

The Red Sox placed left-hander James Paxton on the 15-day injured list Monday with a strained right calf, a day after he limped off the field in the first inning following a quick move trying to cover first base.

“MRI this morning, they got the results,” Red Sox Manager Alex Cora said before Boston faced Texas in the opener of a three-game series. “He’s in pain. We’ll see what happens.”

The 35-year-old Paxton turned quickly and was heading off the mound on Yordan Alvarez’s grounder to first baseman Dominic Smith. He looked back at the mound briefly, then went down to one knee and struggled to put weight on the leg when he got up.

“I felt like I got kicked in the calf. Then, I kind of turned around, took another step and I felt it again,” Paxton said after the Astros beat the Red Sox 10-2. “I was like: ‘It’s not good. It’s my calf.’ I felt it pop.”

Along with Paxton going on the IL, the Red Sox made a handful of other moves.

Monday’s starter Brayan Bello was reinstated from the paternity list, and they recalled lefty Bailey Horn from Triple-A Worcester.

They also selected right-hander Chase Shugart and catcher/infielder Mickey Gasper from Worcester.

In addition, they sent pitchers Brennan Bernardino and Brad Keller to Worcester and designated Jamie Westbrook for assignment.

DODGERS: Mookie Betts is back with the Los Angeles Dodgers after missing nearly two months with a broken left hand.

The Dodgers announced before their Monday night game with the Milwaukee Brewers that they had activated the eight-time All-Star and 2018 AL MVP from the injured list. The Dodgers’ starting lineup had Betts batting second and playing right field.

Betts, who turns 32 on Oct. 7, was batting .304 with a .405 on-base percentage, 10 homers, 40 RBI and nine steals in 72 games when he went on the injured list June 17. Betts suffered the injury when he was hit by a 97.9 mph fastball from Kansas City Royals reliever Dan Altavilla on June 16.

Although Betts was primarily playing shortstop and batting leadoff before his injury, Dodgers Manager Dave Roberts said last week that the team would move him to right field and have him bat second upon his return.

That move would enable two-time AL MVP Shohei Ohtani to remain in the leadoff spot, where he has hit extremely well since Betts’ injury.

Los Angeles made room for him by designating utilityman Amed Rosario for assignment. Rosario, 28, had batted .273 with a .333 on-base percentage, no homers, two RBI and one steal in five games since the Dodgers acquired him from Tampa Bay last month.

Rosario had hit .307 with a .331 on-base percentage, two homers, 26 RBI and nine steals in 76 games with Tampa Bay.

RAYS: Pitcher Ryan Pepiot could return to the rotation late this week after being hospitalized last month for a knee infection that is believed to the result of a spider bite during the All-Star break.

Pepiot was admitted to Columbia University Medical Center in New York and received antibiotics in his right knee after being placed on the 15-day injured list on July 19.

Pepiot had some bug bites while playing golf during the break, but made the trip for a series at the New York Yankees.

The swelling in his knee reached a point where he needed help to walk into the hospital.

ASTROS: Justin Verlander is set to make his second minor league rehab start this week and could rejoin Houston’s rotation after that.

The 41-year-old right-hander took his first step toward returning to the Astros by pitching three innings for Triple-A Sugar Land on Saturday night. The three-time Cy Young Award winner is coming back from neck stiffness that’s sidelined him for two months.

“He bounced back well,” Houston manager Joe Espada said before Monday night’s game at Tampa Bay. “He feels well. He feels good.”

Verlander hasn’t pitched in the majors since June 9. He also missed the beginning of the season with right shoulder inflammation before going 3-2 with a 3.95 ERA in 10 starts. He made his season debut April 19.

MARINERS: Seattle and outfielder Victor Robles reached agreement on a two-year contract extension worth $9.75 million, according to a person with knowledge of the deal.

The deal also includes a $9 million option for the 2027 season.

Robles has been a revelation for Seattle after being acquired from Washington. Robles first struggled to get playing time but once he cracked the lineup has been a significant contributor for the Mariners in their push for the postseason.

Robles is hitting .303 with seven doubles and three homers in 42 games since joining the Mariners. He’s also been excellent as the primary center fielder for Seattle for the past three weeks with Julio Rodriguez sidelined by an ankle injury.