Carlos Martínez is already looking forward to his next start.

The right-hander’s long awaited return to the rotation didn’t go as planned in the Cardinals’ 6-3 loss to the Twins, with Martínez allowing six runs on seven hits across 3 2/3 innings Tuesday night at Target Field. The Twins thumped Martínez for five runs in the second inning, and the Cardinals couldn’t recover from the early deficit despite home runs from Tyler O'Neill -- a two-run, 438-foot shot in the fourth -- and Tommy Edman in the eighth.

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“I feel good, I feel great with my arm,” Martínez said. “I feel like I’m competing. Just some things happened sometimes, and just keep going to try to help the team and keep going to work hard.”

Two days shy of the two-year anniversary of his last start, the two-time All-Star was greeted with a slugging Twins lineup for his season debut. Martínez has long expressed his desire to get back to the rotation after two years in the bullpen. He was the Cardinals primary closer last season, but his eyes were set on the rotation this year. The 28-year-old worked up to a starter’s workload over the offseason and maintained it during the break before Summer Camp began. He impressed the Cardinals with his dedication and earned a spot in the rotation heading into the last week of Summer Camp.

On Tuesday, he faced trouble early with an adventurous first inning. He loaded the bases with a wild pickoff attempt and an intentional walk, but he made the pitch he needed to and got out of the jam with a ground ball.

“That wasn’t a surprise for me, the first inning,” Martínez said. “I’m going to compete. I know the first inning, a lot of movement, the ground balls, covering first base, but I’m ready for everything. Sometimes I need to work extra.”

The second inning unraveled quicker.

After hitting a leadoff single and advancing to third on a double, Luis Arraez scored on a fielder’s choice, when shortstop Paul DeJong chose to throw home. DeJong fielded the ball -- which had a 109.7 mph exit velocity off Byron Buxton’s bat -- deep in the infield and threw high to Yadier Molina, who couldn’t get the tag down in time.

Max Kepler’s RBI single extended the inning, and Josh Donaldson’s sacrifice fly scored the third run -- and was the first out of the inning. Then Martínez’s 91-mph fastball to Jorge Polanco veered back over the plate, and the Twins shortstop put it in the right-field seats for two runs.

Martínez got out of the inning and got through an efficient third inning in 14 pitches, but Donaldson’s two-out solo homer in the fourth forced Martínez from the game after 73 pitches.

“I tried to be away, with the last homer, and with the first homer, I was trying to be inside the zone,” Martínez said. “[It came] to the middle. … I was trying to be focused on home plate, and I was attacking the zone. I don’t know. That was a little bit frustrating for me because I was attacking the zone. They hit good pitches.”

Martínez’s return to the rotation comes on the same day the Cardinals faced their first disruption of the season. Less than a week after the Cardinals had enough starters to transition three of them to the bullpen, Miles Mikolas went on the injured list with a season-ending forearm strain, opening up a fifth spot in the rotation. Martínez’s presence in the rotation now carries more weight than it already did in a shortened, 60-game season. Daniel Ponce de Leon will replace Mikolas on Wednesday, starting the finale of the two-game trip to Minnesota. Left-hander Austin Gomber -- who threw 1 2/3 scoreless innings Tuesday -- will remain the Cardinals’ versatile reliever, and lefty Kwang Hyun Kim is the closer for now.

Despite the early struggles, manager Mike Shildt expects Martínez will rebound from Tuesday’s start.

“You can look at it like a good-hitting club made him pay for some mistakes, and then you can also easily say the guy got better as the game went,” Shildt said. “Carlos is going to be fine. That’s probably my wrap-up point. I’m not concerned about Carlos.

“He didn’t get away with some mistakes, and they made him pay … you can’t overlook it, but outside of that, he was pretty darn effective. Wiggled out of some damage in the first. Made pitches.”

Martínez is eyeing the next time he starts, which likely will be Monday against the Tigers, if the Cardinals stay on their current rotation schedule.

“I feel great, I feel strong,” Martínez said. “Let’s see what happens in the next start.”