Corbin Burnes insisted he felt fine, but it appeared from the start that something wasn’t right. And after fighting for 11 outs without his best stuff on the biggest night of his breakthrough season, the right-hander was forced to retreat from the mound with a member of Milwaukee’s athletic training staff at his side.

The diagnosis arrived during the middle innings of the Brewers’ 4-2 loss to the Cardinals at Busch Stadium on Thursday and he was placed on the 10-day injured list with a left oblique strain on Friday. Infielder Ryon Healy and right-hander J.P. Feyereisen (29th man for a doubleheader) were recalled from the Alternate Training Site.

It was a double blow for a Milwaukee team that had its best starter on the mound for the opener of a five-game sprint to the finish in St. Louis, and a heartbreaker for Burnes, who was denied a chance to properly complete his National League Cy Young Award résumé.

• Box score

It happened on a day that the Brewers could have gained significant ground in the crowded chase for the postseason, since the Giants lost, the Reds and Phillies were idle, and the Brewers were playing another of the teams they’re chasing. Instead, the Brewers fell two games behind the Cards for second place -- and a postseason berth -- in the National League Central, and they remained one game back of the field for the final NL Wild Card spot.

“You never want to end the season banged-up,” Burnes said. “Unfortunately, that's just how this start ended up. I'm definitely pleased with how the year went, but the personal side of it is pushed aside knowing that we are this close to the postseason.”

If this was it for Burnes’ regular season, it was a cruel end to a wonderful year for the 25-year-old, who entered the night neck-and-neck with the Reds’ Trevor Bauer for the National League ERA title, and among the league leaders in every pitching category.

But Burnes walked the first batter he faced in a 24-pitch first inning, threw 22 pitches in the second and 22 more in the third before finally succumbing in the fourth. Brewers manager Craig Counsell, pitching coach Chris Hook and head athletic trainer Scott Barringer all visited Burnes after he walked Dexter Fowler, and they were sent away before Burnes surrendered a tiebreaking, two-run home run to Cardinals No. 9 hitter Dylan Carlson for a 3-1 St. Louis lead.

When Burnes misfired a curveball to the next batter, Kolten Wong, Barringer began a return trip to the mound and Burnes passed him on the way to the dugout.

The discomfort, Burnes said, began in his last start, a scoreless, 100-pitch outing against the Reds five days earlier. But after treatment and a successful bullpen session, he took the mound Thursday at close to 100 percent, and he said he was still “feeling good” despite the look of those arduous early innings. 

“He was trying to get through it when we needed him. We needed him in a big way tonight,” Counsell said. “I think sometimes these guys are going to go out there not being 100 percent. I think he was pretty close to it at the start of the night, but I think it kind of deteriorated as the game went on."

Right-hander Eric Yardley took over, as Counsell and Hook began to strategize the rest of the game and this series with huge postseason implications, which pits the Brewers and Cardinals for five games in four days, including a doubleheader on Friday in which the Brewers have a bullpen day planned for Game 2.

“Coming down the stretch like this, knowing how close we are to the postseason, it's tough to go out there and not get through four innings and make it tough on the bullpen, really for the rest of the weekend,” Burnes said. “You're a little disappointed for letting the team down there.”

Despite the way Thursday ended, it has been a season to remember for Burnes, who had an 8.82 ERA in 49 innings in 2019 and spent the winter remaking himself. He underwent Lasik surgery, worked extensively with a sports psychologist, and logged hours in the Brewers’ high-tech pitching lab in Phoenix to reconfigure his arsenal, elevating a cut fastball that became one of the most effective pitches in MLB.

Before Bauer took the mound and fired eight innings of one-run ball against the Brewers in a 6-1 loss on Wednesday, Burnes led the NL with a 1.77 ERA and had a chance to be Milwaukee’s first league ERA champion since the Milwaukee Braves’ Warren Spahn in 1961.

But with Thursday’s performance -- 3 2/3 innings, six hits, three earned runs, two walks and five strikeouts -- Burnes not only saw his ERA rise to 2.11, but he was stuck on 59 2/3 innings for the season, one shy of the innings he would need to rank among the league’s qualifiers, assuming the Brewers play all 60 games.

Could Burnes pick up an inning or two before the final pitch of the regular season, if he’s healthy and needed? None of the parties were ready to completely rule it out, saying it would depend how Burnes felt on Friday.