Teammates mobbed Heyward near home plate after the towering, walk-off blast, which marked his third career grand slam. He drilled a high fastball into the right field bleachers to even the series at one game apiece.

Anthony Rizzo also homered for Chicago, which improved to 16-12 at home. The Cubs trailed by two runs before loading the bases in the ninth to set up Heyward's heroics.

The blast spoiled a milestone night for Phillies rookie Dylan Cozens, who hit his first career homer, a tiebreaking, two-run shot in the top of the ninth to give the Phillies a 5-3 lead. The homer came in the sixth career at-bat for the 24-year-old.

Aaron Altherr also ripped a three-run home run to help the Phillies erase a three-run deficit.

Adam Morgan (0-2) drew the loss after allowing Heyward's finishing blast.

Cory Mazzoni (1-0) recorded the final two outs for the Cubs to earn his first career victory.

Cubs left-hander Jose Quintana earned a no-decision despite striking out a season-high 10 batters in 5 2/3 innings. He allowed two runs on three hits and two walks.

Phillies right-hander Aaron Nola also wound up with a no-decision. He gave up three runs on four hits in six innings, walking four and striking out six.

Philadelphia trailed 3-0 with two on and two outs in the sixth. Cubs manager Joe Maddon lifted Quintana after 91 pitches and replace him with Steve Cishek, who entered the game with a 1.73 ERA.

Altherr belted Cishek's first pitch to straightaway center field for a three-run home run to even the score. The blast marked Altherr's sixth home run of the season and his first since May 21.

Chicago opened the scoring with Rizzo's leadoff shot in the second.

The Cubs plated two more runs in the fourth to grab a 3-0 advantage. Willson Contreras singled to left field to score Kris Bryant, and Javier Baez hit a sacrifice fly two batters later to score Rizzo.

Hall of Fame quarterback Joe Namath threw out the ceremonial first pitch with Maddon kneeling behind the plate.

--Field Level Media