DENVER — The Cubs pulled off a pair of matching moves to put right-hander Mark Leiter Jr. on the roster ahead of his departure in a 9-6 loss to the Rockies on Saturday.

To open up an active roster spot for Leiter, the Cubs moved to first baseman/outfielder Alfonso Rivas at Triple-A after the Cubs’ 6-5 loss at Coors Field on Friday. Rivas, who made his debut last year, has a hit in every game he’s appeared in this season, going 2-for-4.

“The first thing I say when these things happen is, ‘This sucks, for all of us,'” Cubs manager David Ross said. “It’s part of the options game, when you have to make a move for a pitcher. … The guy swings the bat well, he’s very professional at his job, he’s a great defensive first baseman, he gives you quality at bat every time. He’s a winning player. I believe in him, he believes in himself. So it’s just one of those, ‘Hey, go get some regular bats. We’ll see you soon.'”

To make room for Leiter on the 40-man roster, the Cubs designated right-hander Cory Abbott for assignment.

Leiter’s outing started strong, striking out seven of the first eight batters he faced. But the game eluded Leiter in the third set.

He walked four in the third and fourth innings and gave up a 466-foot homer to CJ Cron. Leiter left the game with one out in the fourth and was charged with seven runs on five hits.

“I think I just fell a bit behind, maybe not as much as I was,” Leiter said. “They made good adjustments, and I didn’t follow.”

Leiter’s departure on Saturday marked his first major league appearance since 2018. He underwent Tommy John surgery in 2019 and last year pitched in the minors.

“A lot of emotions in the last two years, a lot of adrenaline,” said Leiter. “And I’m proud to be back and in a game like this, but I want to be better than that.”

In other list news

The Cubs also acted on a clause from pitcher Locke St. John’s contract, adding him to the roster of 40 men to keep him in the organization. They selected his Triple-A contract, then opted for Iowa. It provides southpaw depth to the club.

To make room for St. John on the roster, the Cubs designated outfielder Greg Deichmann for assignment.

Injury Updates

Cubs left-hander Wade Miley (inflamed left elbow) threw the mound Saturday for the first time since the team stopped him in spring training. He threw 15 pitches and the Cubs will assess his recovery before determining next steps.

Right-hander Alec Mills (lower back injury) was scheduled to pitch a bullpen Saturday in Arizona.

Both pitchers started the season on the 10-day IL, a blow to the Cubs’ rotational depth.