Cardinals star catcher Yadier Molina exited with a sprained left thumb suffered as the Cubs ran out of late scoring chances, and St. Louis ended Chicago's five-game winning streak and avoided a sweep with a 4-3 win Sunday.
The Cardinals moved six games ahead of Chicago in the NL Central. The Pirates were still playing Sunday and are 4 1/2 back of St. Louis.
Molina said he'll have an MRI on the thumb Monday.
Starlin Castro started the ninth with a single, but pinch-runner Quintin Berry was thrown out trying to steal second by Molina's replacement, Tony Cruz. Trevor Rosenthal then struck out Jorge Soler and got Kyle Schwarber to ground out for his 46th save in 48 chances.
St. Louis became the first team to clinch a postseason berth - its fifth straight - on Saturday when San Francisco lost.
Martinez retired 11 straight at one point and finished with six strikeouts. His only trouble came in the third, when he walked two then allowed a two-run single to Rizzo.
Lester labored despite entering the game with a string of three solid starts in which he allowed four runs in 21 innings. He allowed four runs in six innings while striking out seven.
Lester was 1 for 2 at the plate. He's 3 for 11 against St. Louis and 0 for 82 against all other teams.
Pham, the game's second hitter, launched a drive down the left field line over the bleachers onto the street. It was his fifth homer of the season and fourth in his last six games. One out later, Piscotty lined a two-run shot to left.
Cardinals: 2B Kolten Wong, hit by two pitches Saturday, said he was not injured, but was upset ''by the fact that not once, but twice, I got hit.''. OF Randal Grichuk, who was on the DL in August with an elbow injury, ''is still limited'' in the distance he can throw, according to manager Mike Matheny.
Maddon also delivered on a promised ''day at the beach'' to Strop for earning his third save. Before the game, a beach chair - arranged with bottles of beer in an ice bucket, a margarita and other paraphernalia - was set up in front of Strop's locker. ''I wanted to really make it really emphatic that he was not playing,'' Maddon said.
Cardinals: LHP Jaime Garcia (9-5, 2.52) faces Cincinnati LHP John Lamb as St. Louis opens a three-game series and its final homestand against the Reds. Garcia is 6-1 with a 3.02 ERA since Aug. 1.
Cubs: RHP Jason Hammel (8-6, 3.73) takes the mound against Milwaukee RHP Wily Peralta (5-9, 4.41) as the Cubs continue their 10-game homestand. Although Hammel is 2-1 in his last five starts, he's allowed 16 runs in 26 innings for a 5.54 ERA during the span.
Link to box score: St. Louis (93-56) 4 at C hicago Cubs (87-62) 3