ST. LOUIS -- It was a milestone day for Jordan Hicks, though not a winning one.

Returning to St. Louis to face the team he played for most of the first five seasons of his career, Hicks reached a new career high in innings in a single season, but he still received a rude welcome from his former Cardinals teammates, who tagged him for a career-high five earned runs over four frames in the Giants’ 9-4 loss on a scorching Saturday afternoon at Busch Stadium.

Hicks, a converted reliever, entered Saturday only one inning shy of his previous personal best (77 2/3 innings), which he set during his rookie season with the Cardinals in 2018. He took the mound in the bottom of the first with a three-run lead thanks to an RBI single from Jorge Soler and a two-run single from Michael Conforto, though St. Louis quickly pulled within one behind Paul Goldschmidt’s two-run blast out to left-center field.

Hicks took a 4-2 lead into the fourth, but he surrendered a back-breaking, three-run homer to Alec Burleson with two outs, swinging the game in favor of the Cardinals. Hicks didn’t have his best control, walking three and hitting one batter, and said he felt his lower-body stamina wane after grinding through a 29-pitch third in the steamy conditions.

“I would say my legs were pretty dead after the third, to be honest,” Hicks said. “It’s just one of those things. I could always see it when I was on the Cardinals, that the other pitchers looked like they were pretty dead out there. You get them up to 20-30 pitches in an inning, that’s when we usually did our damage when I was with the Cardinals. It made sense that last inning.”

The Giants opted to turn to their bullpen in the fifth, leaving Hicks with a 3.24 ERA over 80 2/3 innings less than halfway through his first season as a full-time starter.

“First time ever above 80 innings,” Hicks said. “I’ll take a few positives from today. Overall, I got beat on two pitches in my eyes and could have obviously put myself in a better position so they wouldn’t have been two-run homers or three-run homers. It’s hard to feel terrible about how today went, but at the same time, I know I could have executed better and things probably would have went a lot differently.”

Hicks has failed to complete five innings in three of his past four outings, though he said his arm feels good and is looking forward to turning the page and getting back on track once the Giants return to San Francisco.

“He keeps himself in great shape,” manager Bob Melvin said. “Obviously, there’s going to be periods where the velo is going to be down and maybe not as crisp with some of his breaking stuff, which you’re seeing right now. Whether that’s where he is in the innings right now, I’m not sure, but the last few games, they’ve made him work pretty hard.”

The Giants will have to find a way to manage Hicks’ workload at some point this summer, though they can ill-afford to give the 27-year-old right-hander a blow right now. With Keaton Winn (right elbow inflammation) joining Blake Snell (left groin strain), Kyle Harrison (right ankle sprain), Robbie Ray (Tommy John surgery) and Alex Cobb (left hip surgery) on the injured list on Saturday, the Giants’ rotation is officially down to two traditional starters: Hicks and Logan Webb, who will start Sunday’s series finale and try to prevent the Cardinals from completing a three-game sweep.

The Giants should have more help down the line, as Snell and Ray are scheduled to pitch in a rehab game with Triple-A Sacramento on Sunday. Snell will start and throw approximately 50 pitches; if all goes well, he could be a candidate to rejoin San Francisco’s rotation next week. Harrison could be back after his requisite 15 days on the IL are up, with Ray and Cobb likely to follow sometime around the All-Star break.

While reinforcements are coming, the Giants will have to piece it together until then and continue to lean heavily on their bullpen, which leads the Majors with 313 innings pitched this year.

“It’s been a huge workload for them,” Hicks said. “Just the way they’re handling it, going about it, is pretty cool to see, and the success that they’re having at the same time. Hopefully they can just stay healthy and keep going, but hopefully as the season progresses, we’ll get some guys back and we can go longer in games. That’ll definitely help, but the guys are doing a great job.”