Kris Bryant hit a 495-foot homer, but it wasn't even the biggest blast of the day for the Cubs.
Miguel Montero hit a grand slam and Jonathan Herrera hit a pinch-hit homer in the sixth as the Cubs (78-57) finished off a sweep of the Diamondbacks (65-72) with a 6-4 victory in front of 41,183 fans at Wrigley Field Saturday.
Montero - whom the Cubs acquired from Arizona over the winter - had a single and a walk against his former team apart from the game-winning grand slam that followed a Bryant walk in the sixth.
"Every win is important," Montero said. "At this point, you can't really think of other things. You just have to think about winning and the rest will take care of itself."
Bryant got things started with his record-setting shot in the fifth inning, crushing an 0-2 pitch from Arizona starter Rubby De La Rosa off the top of the video board in left field.
Kyle Hendricks started for the Cubs and allowed only one run in five innings, but the game was still tied when he exited so Justin Grimm earned the win.
The Diamondbacks mounted a little rally in the bottom of the ninth as former Cub Welington Castillo homered and then Arizona shortstop Nick Ahmed hit a two-run blast three batters later.
The Cubs are 17-4 at home over their last 21 games and have hit homers in 15 straight contests at Wrigley Field.
Bryant and the Cubs also lead the majors with 48 homers over their last 24 games, dating back to Aug. 12.
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The Cubs head to St. Louis Monday for an important three-game series against the Cardinals, riding the momentum from this sweep.
"It's big. You want to go in with momentum," Hendricks said. "We've been playing well lately, so just winning ballgames is huge. Keeps the morale up around and just going in there with some momentum is good for us."