ST. LOUIS -- One big inning was all the St. Louis Cardinals needed to beat its old teammate again.
The Cardinals scored all four of their runs in the bottom of the fourth Sunday to hand Milwaukee Brewers starter Kyle Lohse, their No. 1 starter from a year ago, a third loss in just over a month with a 4-2 decision.
Rookie John Gast (2-0) won his second start in place of the injured Jake Westbrook, working 5 1/3 innings and allowing both Brewers runs. The bullpen picked up the last 11 outs, with Edward Mujica converting his 13th straight save opportunity.
Lohse (1-5) went 16-3 for St. Louis last season, but signed with Milwaukee as a free agent in late March after failing to land a more lucrative deal in the winter. He's pitched to a 3.76 earned run average, but the Brewers have scored just 19 runs in his nine starts.
After retiring nine of the first 10 men he faced, Lohse gave up six hits in the fourth. Carlos Beltran and Allen Craig singled ahead of Yadier Molina's bouncer up the middle that scored Beltran for a 1-0 lead.
Jon Jay added an RBI double down the right field line, making it 2-0, and David Freese lined a single to right which plated Molina. Pete Kozma capped the outburst with a perfect suicide squeeze bunt that turned into a single, scoring Jay with the fourth run.
Yuniesky Betancourt and Jeff Bianchi collected RBI singles for Milwaukee (17-25), which blew a bases-loaded, no-out chance against reliever Seth Maness in the seventh. Jean Segura popped out and Ryan Braun bounced into a 5-4-3 double play.
The Cardinals (28-15) closed out their 10-game homestand at 7-3 and improved to 8-2 against the Brewers this year. They extended their National League Central lead over the Cincinnati Reds and Pittsburgh Pirates to 2 1/2 games.
NOTES: Milwaukee 3B Aramis Ramirez sat out Sunday's game to rest his left knee, which forced him on the disabled list for 23 games earlier this season. Manager Ron Roenicke is being cautious with Ramirez in terms of playing him in day games after night games ... St. Louis announced Sunday that it will call up LHP Tyler Lyons and start him Wednesday night at the San Diego Padres. Lyons, who will make his Major League debut, is 2-1 with a 4.47 earned run average in eight starts for Class AAA Memphis of the Pacific Coast League ... Cardinals RHP Chris Carpenter threw three innings in a simulated game on Saturday and reported no soreness in his shoulder. He'll throw a side session Monday and a four-inning simulated game Thursday before deciding on the next step in his rehab from a nerve condition.