One big swing by Mark Reynolds and a once-imposing deficit was down to a single run.
Tony Cruz put the St. Louis Cardinals over the top. This time, they didn't wait until the final at-bat.
''This is ridiculous,'' said Reynolds, whose grand slam started the comeback in a 10-9 victory over the Chicago Cubs on Monday night. ''We're never out of it.''
Cruz hit a tiebreaking two-run double to cap a four-run seventh inning for the Cardinals, who have won seven in a row.
''It's just a team full of guys who grind out every inning, every out, every pitch,'' said Cruz, who caught on a rare day off for Yadier Molina. ''I can't pinpoint one thing. It's all just a team effort.''
The NL Central leaders trailed 5-0 in the first before Reynolds hit his fourth career grand slam in the bottom half. They improved to 19-6 for the franchise's best start since 1900.
''A lot of game left, we don't have the bat in our hands yet,'' manager Mike Matheny said. ''They just talked about chipping away. The mood never changed.''
Miguel Socolovich (2-0) allowed a hit in a scoreless seventh and Seth Maness gave up a homer to rookie Addison Russell with two outs in the ninth before earning his second save. The Cardinals rested closer Trevor Rosenthal and other weary relievers after sweeping the Pirates in a weekend series totaling 35 innings with all three games decided in extra innings by a total score of 7-4.
Miguel Montero had two hits and three RBIs and pitcher Travis Wood had an RBI in the first for the Cubs, who jumped on Carlos Martinez. Anthony Rizzo homered and Kris Bryant had an infield hit and four walks for Chicago, which has lost four of five.
''Your team puts up five in the first, you can't give it back,'' Wood said. ''That's all on me.''
The Cardinals loaded the bases on two singles and a walk to start the seventh against Pedro Strop (0-2).
''He's been outstanding; he is outstanding,'' manager Joe Maddon said. ''Just a tough night for him. That was our best opportunity to win the game.''
Kolten Wong's single off Zac Rosscup tied it ahead of the double just inside the third-base line through a drawn-in infield by Cruz, who caught on a rare day off for Yadier Molina. Wong homered in the 14th to beat the Pirates 3-2 on Sunday.
Martinez walked three of the first four hitters and was charged with a career-worst seven runs in a season-low 3 2-3 innings. He entered among the league leaders with a 1.73 ERA and had won his three previous starts.
The 19-6 record by St. Louis tops 18-6 starts by the 1941 and 1944 teams.
Cubs: Denorfia was 2 for 2 with an RBI before aggravating a left hamstring strain sliding into third in the third, and was replaced by Junior Lake. Maddon said Denorfia would be placed on the 15-day disabled list. ''I hit second a little awkwardly and when I tried to get back to sprinting speed, I felt a little something,'' Denorfia said. ''I took the five minutes to feel bad for myself and I'm just kind of moving on.''
Cardinals: Matt Carpenter was 0 for 5 a day after being removed after seven innings Sunday due to dizziness, but leaving the ballpark feeling fine after replenishing fluids.
Two fans raced onto the field in the top of the sixth. The first was quickly tackled but the second evaded personnel long enough to somersault onto home plate.
Cubs: Left-handed hitters are batting .343 against Kyle Hendricks (0-1, 5.23), and the Cardinals have five of them who start.
Cardinals: Lefty Tyler Lyons makes his first start of the season after being recalled from Triple-A Memphis. He's the second pitcher in two starts to take the spot of ace Adam Wainwright, out for the year with a torn left Achilles.
Link to box score: St. Louis (19-6) 10, Chicago Cubs (13-11) 9