That player was Alex Bregman, who homered twice, his second a tiebreaking two-run shot in the sixth inning that propelled the injury-weakened Astros to a 9-6 win that gave manager AJ Hinch his 500th career victory.
Bregman, who is tied for the American League lead with 17 homers, got his first one in the third inning off starter Jon Lester (3-4). It was tied at 6-6 when he connected on Brad Brach's first pitch for the second.
Bregman's big game helped the Astros overcome five home runs by the Cubs on a night Houston played with a lineup peppered with recent reinforcements from Triple-A as stars Jose Altuve, George Springer and Carlos Correa sat out with injuries.
''He's such an emotional leader for us ... he provides that spark with the at-bats, the posture, the walks, the intensity that he conducts his at-bats,'' Hinch said.
Bregman has a franchise-record 12 home runs this month, passing Jimmy Wynn, who had 11 in May 1969.
He said he doesn't view the team's new additions as Triple-A players and believes they are all capable of contributing.
''All of them need to know that they belong, have a ton of confidence and be proud that they're helping win big league baseball games,'' he said.
Roberto Osuna struck out one in a perfect ninth for his 15th save.
David Bote homered twice for the Cubs and Jason Heyward, Addison Russell and Kyle Schwarber each hit one. The Cubs have piled up 21 home runs in their last seven games, but have only won twice in that stretch.
Houston's Michael Brantley had two hits and two RBIs and catcher Garrett Stubbs added two hits and drove in a run in his major league debut, a day after Jack Mayfield played in his first major league game.
Lester lost his third straight decision by allowing eight hits and a season-high seven earned runs.
''He didn't look far off but it was just a matter of not executing his pitches perfectly and just missing,'' manager Joe Maddon said.
The Astros led by a run when Heyward tied it by opening the second inning with his solo shot off rookie Corbin Martin. The Cubs went back-to-back and took a 2-1 lead when Russell homered for the second straight game on his shot to right-center.
There was one out in the inning when the Cubs went deep again, this time on a shot by Bote, which bounced off the wall above the seats in left field to make it 3-1.
Bregman got Houston within one with his first home run. Mayfield walked with no outs in the fourth before a one-out double by Jake Marisnick. Stubbs singled to score Mayfield and tie it before an RBI single by Derek Fisher put Houston up 4-3.
Fisher stole second base with two outs and Brantley's double, which bounced off the wall in center field, scored two to push Houston's lead to 6-3.
Bote hit a two-run homer off Josh James (2-0) in the sixth inning and Schwarber tied it at 6-6 with a solo shot on the next at-bat.
Fisher walked with two outs in the sixth to end Lester's night. He was replaced by Brach, who was greeted by Bregman's second homer to put Houston up 8-6. An RBI double by Marisnick extended the lead to 9-6 in the seventh.
Martin yielded five hits and three runs in 3 2/3 innings.
Cubs: INF Kris Bryant sat out for a second straight game after he was injured in an outfield collision with Heyward on Sunday. Maddon said he was feeling better on Tuesday and could play on Wednesday. ... Reliever Pedro Strop allowed one hit in one inning in the first game of a rehabilitation assignment with Triple-A Iowa. He is scheduled to make another appearance on Thursday and could return this weekend.
Astros: Altuve (left hamstring) returned to Houston after playing two games of a rehabilitation assignment at Triple-A Round Rock to be re-evaluated after experiencing fatigue and soreness in his surgically repaired right leg. Altuve had surgery in October to repair a cracked kneecap and has been on the injured list with the hamstring injury since May 11. Hinch said Altuve's hamstring is fine but his other leg is now bothering him. ... Correa sat out on Tuesday after experiencing soreness around his ribs. Correa, who had a scheduled day off on Monday, told Hinch on Tuesday morning that he was dealing with the problem and he is also being evaluated by the team's doctors.
THEY SAID IT
Maddon's tongue in cheek response to all the home runs hit in this series: ''There's something going on, I am not a conspiracy theorist, I am not ... (but) I don't know if it's a combination of the ball, maybe the bat. Maybe the technology in the bat's gotten better. Maybe it's purely about velocity or maybe there's helium in this ballpark. I have no idea. It's jumping.''
Cubs: RHP Kyle Hendricks (4-4, 3.34 ERA) will start for Chicago in the finale of this series on Wednesday night. Hendricks allowed six hits and three runs in six innings in his last start but did not factor into the decision in a 6-5 loss to the Reds.
Astros: LHP Wade Miley (5-2, 3.32) is scheduled to start for the Astros on Wednesday. Miley struck out a season-high eight in his last start to extend his winning streak to four games.
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