Rizzo homered for the third time in five games with three RBI and Lester had a strong outing for the Chicago Cubs, who ended the St. Louis Cardinals' eight-game winning streak and their own four-game skid with a 6-5 victory on Wednesday night.
''What did they have, two runners on the last inning?'' said rookie Kris Bryant, who had two hits and an RBI. ''It was huge for us to get that win.''
Jhonny Peralta hit a 447-foot homer and Yadier Molina had two hits and two RBIs for the Cardinals, who erased deficits of five and three runs the first two games of the four-game series but couldn't quite make up a three-run, fifth-inning deficit. Lance Lynn (1-3) allowed five runs in six innings.
''I just think this is who we are,'' manager Mike Matheny said. ''We're just going to keep coming. Regardless of what's happened in recent games, just keep playing.''
St. Louis put runners on the corners with one out in the ninth before Hector Rondon escaped for his sixth save in seven chances.
The Cardinals entered a major league-best 20-6, the best start for the franchise since 1900, and their National League Central lead was shaved to 5-1/2 games over the second-place Cubs. They're 13-3 at home.
Lester (2-2) left leading 5-4 after seven innings but only one of the runs was earned against the team he dominated in St. Louis in Game 5 of the 2013 World Series. He's worked seven innings in each of the last two starts.
The pitcher's fielding error covering first led to a run in the second and second baseman Addison Russell missed a liner for a fielding error that led to two more runs in the sixth.
Lester also mishandled a cutoff throw on pinch hitter Kolten Wong's RBI single in the eighth.
''It should have been a little bit easier,'' Lester said. ''I made it a little bit harder. If I catch two balls, maybe we save some guys in the bullpen.''
Rizzo hit his fifth homer in the third and added a two-run double in the fifth. He also homered in the series opener Monday and had three hits and a walk on Tuesday.
''I think he's one of the top five best at-bats in all of baseball,'' said manager Joe Maddon, who was ejected in the sixth for arguing balls and strikes. ''This guy is engaged in every pitch. He doesn't give anything away at any time.''
Molina has 82 RBI against the Cubs, most against any opponent.
Mark Reynolds was 0 for 5 in the cleanup spot for the Cardinals, cooling off after hitting the tie-breaking RBI double as a pinch hitter on Tuesday and starting St. Louis' comeback with a first-inning grand slam on Monday.
The ejection was Maddon's second of the season and 40th of his career. He didn't let up on plate umpire D.J. Reyburn after the game.
''The whole game was egregiously bad,'' Maddon said. ''You cannot permit that to happen. We're trying to ascend and were not going to take that from anybody, anywhere, at any time.''
Link to box score: Chicago Cubs (14-12) 6 at St. Louis (20-7) 5