Besides falling four games back in the NL Central, the St. Louis Cardinals also lost a key arm.

Rookie reliever Lance Lynn injured a left side muscle in the eighth inning after working 1 2-3 innings of relief with three strikeouts in a 5-3 loss to the Milwaukee Brewers on Tuesday night. Manager Tony La Russa expects the right-hander, who has developed into a consistent setup option, to be placed on the 15-day disabled list.

"I think it would be hard to avoid it," La Russa said. "He's been very useful, a key contributor. We'll find somebody else."

Casey McGehee's double snapped a 10th-inning tie and Milwaukee won for the 12th time in 13 games, dealing another blow to their closest pursuers in the division. The Cardinals and Brewers have eight games remaining.

"I remember with the Astros being nine back of this club with about 11 games left in the season and we almost tied them, so anything can happen," Lance Berkman said. "When you have a chance to play the team that's in front of you, you would like to take advantage of it, but they're in front of us for a reason.

"Because they have a great team. And they're going to be tough to beat."

Lynn was injured on a full-count walk to pinch hitter George Kottaras with two outs in the eighth. The right-hander bent over in pain, but eventually walked off the field.

"I think it was the last pitch," La Russa said. "It was the first time he showed anything."

The Brewers' 3-4-5 hitters had been 0 for 12 before extra innings when Prince Fielder singled to put runners at the corners ahead of McGehee's double off Octavio Dotel (0-1). Yuniesky Betancourt added a sacrifice fly and John Axford finished for his 30th straight save and 33rd in 35 chances overall.

David Freese had an RBI single in his first game back from a concussion sustained from a beanball last Thursday for the Cardinals, who fell four games back after the opener of a three-game series. Gerald Laird had two hits and an RBI but Albert Pujols was 0 for 5 with no tough outs and missed a chance to end it in the ninth against LaTroy Hawkins (1-0), popping out to right with two on and two outs.

The Cardinals are the only team to beat the Brewers during their run, but have lost three of four to them the last eight days. They are four games behind for the first time since April 12, disappointing a sellout crowd of 40,626.

"You don't want to put any extra pressure on yourself," starter Edwin Jackson said. "Go out and play relaxed, and do what we do."

Both teams have backed up their vow thus far to avoid shenanigans after tempers flared last week when Pujols was hit on the hand with a pitch high and tight and the Cardinals retaliated by hitting Ryan Braun.

Leadoff man Corey Hart gave the Brewers a 2-0 lead in the third with his 17th homer, returning after missing only one game because of a bruised left hand. Jonathan Lucroy had two hits and an RBI.

McGehee had a three-homer day off Jackson last week but was hitless in four at-bats against Jackson and the St. Louis bullpen before getting the go-ahead hit.

The Brewers totaled nine hits against four pitchers, ending a franchise-best run of nine straight games in double figures that matched the best in the majors this season.

Jackson retired the first seven hitters with nothing out of the infield before Lucroy's clean single to left with two outs in the third. Two batters later, Hart homered to straightaway center to put the Brewers up 2-0.

It was the fifth homer the right-hander allowed in 14 2-3 innings against the Brewers, two to Hart and three to McGehee.

The Cardinals tied it in the sixth against Shaun Marcum on RBI singles from Freese and Laird, whose grounder slipped under first baseman Fielder's glove far off the bag.

An inning earlier, Skip Schumaker was ruled out on a tag play at the plate in a controversial call by Angel Hernandez that prompted a vehement protest from La Russa. Replays appeared to indicate that Schumaker had beat Lucroy's tag after a throw from Fielder, although Berkman said Hernandez told the Cardinals that Schumaker never touched the plate with his foot.

The Brewers loaded the bases with no outs in the fifth with the heart of the order ahead, but Braun and Fielder hit first-pitch soft lineouts to the infield and Laird recovered Jackson's ball in the dirt that made it 2-0 against McGehee in plenty of time to catch Marcum in no-man's land between third and home for an inning-ending pickoff.

Notes: Cardinals RHP Jason Motte struck out one in a scoreless seventh and hasn't allowed an earned run in 21 appearances covering 15 innings since June 24. ... The Tigers had nine straight double-figure hit games from June 22-July 1. ... Pujols is 5 for 39 (.128) with no homers and three RBIs against the Brewers. ... Betancourt was 0 for 4 to end a 10-game hitting streak.