Manny Margot drew a four-pitch, bases-loaded walk with one out in the 10th inning and the San Diego Padres overcame an impressive power display by Kris Bryant and Jason Heyward to beat the Cubs 9-8 Tuesday night.
The Cubs' lead for the second NL wild-card spot was cut to one game over Milwaukee and two over Philadelphia.
Bryant hit a pair of two-run homers and Heyward also homered twice and drove in three runs for the Cubs, who rallied from a 6-2 deficit in the third inning to tie it at 8 after Bryant and Heyward each hit their second home run.
But that show was wasted when Steve Cishek loaded the bases on a single and two walks in the 10th, and then issued a third straight walk, to Margot.
Rookie Michel Baez (1-1) pitched the 10th for the win.
Bryant's second homer pulled the Cubs to 8-7 after Anthony Rizzo hit a leadoff single in the eighth. Heyward tied it with his second of the night, a one-out shot to straightaway center. Both came off rookie Andres Munoz.
Cubs starter Jose Quintana went just three innings, giving up six runs - four earned - on seven hits. He struck out one and walked none.
Cole Hamels (7-6, 3.95), who attended San Diego's Rancho Bernardo High, is scheduled to start Wednesday night. He is 9-2 with a 2.45 ERA in 18 career starts against the Padres.
Chris Paddack (8-7, 3.54) will face the Cubs for the first time. On San Diego's last road trip, he threw 12 1/3 innings of one-run ball in starts against San Francisco and Arizona.