SAN DIEGO -- After 50 career appearances, all of them starts, Dinelson Lamet took an unusual and unexpected path to the Petco Park mound on Sunday evening -- through the bullpen gates.

Lamet made his first career relief appearance, an unanticipated development after the right-hander had spent the entirety of his career as a starter.

Lamet relieved left-hander Ryan Weathers in the Padres’ 5-3 victory over the Cardinals on Sunday night. Lamet allowed a run across two innings – his first much better than his second.

“I’d say it was one of my better moments so far,” Lamet said. “Coming into it I was struggling a little bit, but I also feel like every outing I’ve had something to build on, and I’ve been improving.”

The right-hander came out firing, striking out Max Moroff swinging to start his night with a 97.9 mph fastball -- his hardest pitch of the season. Lamet worked a 1-2-3 fifth that ended with two consecutive swing-and-miss sliders to Dylan Carlson.

“I thought the first inning today, that was the most electric, that was the best I’ve seen him this year,” said Padres manager Jayce Tingler.

Lamet’s next inning wasn’t quite as crisp, and his fastball velocity dipped slightly, too. Lamet allowed a leadoff double to Paul Goldschmidt, who came around to score when Yadier Molina bounced into a double play (which was expertly started by Tucupita Marcano at second base). But Lamet worked around a pair of two-out walks to escape the threat by getting Matt Carpenter to bounce to second on a check-swing.

The Padres' decision to move Lamet to the ’pen is a curious one -- but there are certainly circumstances that may have prompted it. Lamet has been built up slowly this season after sustaining a UCL strain last September, which forced him to miss the postseason.

Lamet has made three starts this season but hasn't looked at all like himself. He exited his first start early because of forearm tightness, which landed him on the injured list. When he returned, he was placed on a strict pitch count and lasted just two innings in each of his two most recent starts. His velocity sat several ticks below his usual upper-90s fastball.

In 12 starts last season, Lamet posted a 2.09 ERA, the best qualifying mark for a starting pitcher in franchise history. He finished fourth in the National League Cy Young Award voting. But after a painstakingly slow buildup, Lamet has looked nothing like that electrifying version of himself yet this season.

It's unclear whether Lamet's foray into relief pitching is temporary or more long term. Perhaps the Padres feel Lamet can better rekindle his electrifying fastball/slider combo out of the bullpen right now. They left open the possibility for further relief outings.

“We’re going to stay open-ended,” Tingler said. “We’re going to do two things. No. 1: What’s best for Lamet? And then: What’s best for the team? It could be back-and-forth, it could be back to starting. We’ll just kind of wait and see and see how everything goes.”

It's also possible the Padres are looking for a bit of temporary relief, with lefty Drew Pomeranz (left shoulder impingement) and righty Keone Kela (right forearm tightness) on the IL.

Regardless of his role, Lamet handled Sunday’s relief outing an awful lot like he’d handle a start. He moseyed out to the bullpen between the third and fourth innings, then began to get loose, methodically as the fourth inning unfolded. He knew precisely when he’d be entering the game.

“It was a good experience,” Lamet said. “But at the same time, I prepared and treated it like a starter right now -- same routine as a starter, same mentality as a starter, and it was fine. … I’m treating this the same as a start and maintaining that same routine.”