Mujica converted his first save chance in 18 games, working the last two innings in an 8-4 victory over the Chicago Cubs that ended a four-game losing streak and avoided a sweep on Sunday.
"All the time it's about consistency," Mujica said. "Sometimes days off are pretty good for pitchers. For my arm. Everybody knows we're going to be out of this rough time."
Pete Kozma singled home the tiebreaking run in the sixth. Matt Carpenter and Allen Craig each had three hits and drove in a run. Jon Jay and David Freese both drove in two runs, though they only had one hit between them.
"That was a great at-bat by Pete, and couldn't have come at a better time," manager Mike Matheny said. "I thought the guys did a real good job of situational hitting, getting the runs in when they had money on the table."
Mujica earned his 31st save in 33 chances and first since July 25 against the Phillies, overcoming Starlin Castro's leadoff double in the eighth with just a one-run cushion. Then he retired the final five in a row in an outing that matched his longest of the year.
The right-hander had been anticipating that after setup man Trevor Rosenthal threw 33 pitches and gave up the tying and go-ahead runs in two-thirds of an inning in a 6-5 loss.
"We had that in mind, didn't necessarily commit to that," Matheny said. "We knew that would be an option to go for 'Chief' for two."
Randy Choate (2-1) faced one batter, getting leadoff man David DeJesus to pop out with two men on to end the sixth after the Cubs had tied it at 4 on RBI singles by Castro and Darwin Barney off Seth Maness.
Barney, like Kozma an eighth-place hitter, had two RBI singles. He's batting .215 overall but has a .317 average against St. Louis with two homers and 10 RBIs.
"He battles up there and it's hard to strike him out and he's going to give you an at-bat all the time," Cubs manager Dale Sveum said. "He's a little battler."
The Cardinals combined two singles, a walk, a steal and a sacrifice fly off Edwin Jackson in a three-run first. Matt Holliday had one of the RBIs plus a steal off Jackson's slow move to the plate, before Jackson finally retaliated by picking off Jay.
Holliday handed the Cubs an unearned run in the third when he camped under Junior Lake's two-out high fly to medium left but then whiffed on the catch and DeJesus scored from first.
The Cubs settled for their first series win in St. Louis since a three-game sweep Sept. 13-15, 2010. They'd been 0-6-1 the previous seven series, and were trying for a three-game sweep.
"You can take two out of three here it's definitely a good thing," Barney said. "It's tough to win a series here. They play so well at home and Allen Craig is unbelievable with runners in scoring position."
Cardinals OF Carlos Beltran fouled a ball off his right foot in the fifth, got medical attention on the field and then struck out before leaving with a bruise. X-rays were negative and the Cardinals are hopeful he can return Tuesday against NL Central-leading Pittsburgh. "It's sore, no doubt it's sore," Beltran said. "Hopefully Tuesday I can be back." ... Holliday grounded into his major league-leading 26th double play in the fifth. ... The Cubs' Darnell McDonald walked pinch-hitting in the seventh in his first at-bat of the year. He's the 50th player used by the Cubs, most in the majors. ... St. Louis' last two wins have come in starts by Joe Kelly, who allowed three earned runs in 5 1/3 innings and Jackson gave up four runs in five innings. ... Castro has five hits the last two games and is batting .536 (15-for-28) the last seven games against St. Louis.