Just as Reds starter Sonny Gray was beginning to put together one of his best starts of the season Tuesday, his night ended in a hurry.

Gray was pulled prior to the start of the fourth inning of the 5-1 loss to the Brewers with right groin tightness, being replaced on the mound by lefty Sean Doolittle with Cincinnati up 1-0 at Great American Ball Park. While warming up between innings, Gray felt a pull in his right leg after his first warmup pitch. After a few more pitches, the pain grew.

Gray was met on the mound by catcher Tucker Barnhart, pitching coach Derek Johnson and athletic trainer Tomas Vera, and after a quick conversation, manager David Bell joined them. Gray said he didn’t know if gutting out one more inning might force him to the shelf for a longer period of time, so when the group discussed pulling him, he didn’t fight to stay in the game.

“The first thing in my head was, ‘The smart thing would be to stop. The smart thing to do would be to stop, so you’re not missing eight, 10 weeks here,’” said Gray, who will receive an MRI on Wednesday. “The competitiveness wants to keep going, because I think I can pitch just kind of half-dragging my backside through, but then there’s a lot of repercussions that come with that.”

Gray walked off the mound and into the dugout, putting an end to a solid start in which he had already struck out five Brewers and recorded eight whiffs on 21 swings. Gray started off the game in trouble when Milwaukee first baseman Daniel Vogelbach singled and right fielder Avisaíl García was hit by a pitch two batters later. But Gray induced a popup to end the threat, then struck out three of the last seven batters he faced.

“I felt good coming into this thing. I felt good during it. I was in a great spot,” Gray said. “I was in a good spot, and then I threw the one warmup pitch and I just knew this wasn’t a feeling that I’m going to be able to continue.”

“I thought he was pitching good,” Bell said. “He had it all working. [It is] very frustrating, [but] it is one game. The bigger concern now is hoping he's OK and it's nothing serious, [that] we can get him back before too long. That's where our minds are right now.”

The problem with Gray leaving after three innings? Cincinnati’s bullpen then had to work through the next six, and issues that have plagued the team’s relievers all season quickly became apparent:

• The Reds’ bullpen entered the game with the worst ERA in the Majors (5.78); Doolittle, Ryan Hendrix and Amir Garrett -- the first three relievers out of Cincinnati’s ‘pen -- were charged with three earned runs in three combined innings and Ashton Goudeau gave up two more in the ninth.

• Reds relievers went into the game in a four-way tie in MLB for the most home runs allowed this season (36); on just the second pitch Doolittle threw, García hit a Statcast-projected 380-foot shot to left-center, tying the game at one run apiece.

• Cincinnati relievers’ 125 walks in 2021 were second only to the Cardinals (140) among big league bullpens; Hendrix walked Brewers shortstop Luis Urías and Vogelbach to start the fifth inning, with Urías later scoring the go-ahead run on left fielder Christian Yelich’s double play.

"We caught a break, there's no question,” Brewers manager Craig Counsell said. “[Gray is] a tough customer. The guy who comes in the game, he's unprepared because no one can be prepared for that, and Avi got him right away. We put a tough inning on that, and then it's a bullpen game.”

It didn’t help that the Reds managed just two hits after the third inning and went 1-for-7 with runners in scoring position overall, but the bullpen couldn’t overcome the challenge set by Gray’s early exit.