Ryan Braun and Nyjer Morgan homered for the Brewers, who moved 10 1/2 games ahead of the second-place Cardinals, who swept a three-game set at Milwaukee last week. Corey Hart extended his hitting streak to 17 games with an RBI infield hit in the second inning of the opener of this three-game set.
Wolf (12-9) gave up four hits, a run, walked two and had five strikeouts to win for the sixth time in his last seven decisions. He also had a pair of hits. John Axford retired the side in order in the final inning for his 41st save.
"Every game we play against anybody right now is big, but particularly against the team that's chasing us," Braun said.
Westbrook (11-8), who hadn't lost in his previous three starts, gave up nine hits, but had nine strikeouts over six innings.
"Our whole mindset before we went to Milwaukee was we have to win ball games," Westbrook said. "Losing this one, we still have to come out tomorrow and win the next game. Hopefully, we can do everything we can to put pressure on them."
The Brewers, who swept Houston over the weekend, scored in the second inning. Yuniesky Betancourt doubled with two outs and Wolf's infield hit caromed off Westbrook. Hart then hit a ground ball deep in the hole on the left side. The throw to first from shortstop Rafael Furcal was late, and Betancourt came home.
Braun led off the next inning with his 27th homer of the year, a blast onto the grassy area beyond the wall in center.
St. Louis scored in the fifth on a double-play grounder from Allen Craig. The hit plated David Freese, who led off with a double and advanced thanks to an error on first baseman Prince Fielder during Yadier Molina's at-bat.
Betancourt had three hits...The Cardinals, who had just four hits, had won the previous four against Milwaukee...The Brewers have gone 14-3 over their last 17 road games.