Miguel Montero's grand slam broke a 1-1 tie, and the Chicago Cubs (78-57) rode that drive to a 6-4 victory over the Arizona Diamondbacks (65-72) Sunday afternoon at Wrigley Field. With the win, the Cubs completed a three-game sweep of the D-backs and moved to 21 games over .500.

With the bases loaded and nobody out in the bottom of the sixth, Montero lofted a 1-0 fast ball from Matt Reynolds just beyond the basket and into the left-field bleachers (video). Montero's blast (15) was his third career grand slam, and it followed a lead-off single from Chris Coghlan and back-to-back walks of Anthony Rizzo and Kris Bryant.

One out later, pinch hitter Jonathan Herrera homered to right (2) to make it a five-run lead.

Arizona tallied the game's first run when former Cubs catcher Welington Castillo doubled home David Peralta in the top of the fourth. Cubs pitching, though, overmatched the Diamondbacks' lineup for most of the game until Castillo homered (18) in the ninth off Trevor Cahill. Nick Ahmed later hit a two-run home run (8) off Pedro Strop with two outs.

Chicago tied the game at 1-1 in the bottom of the fifth on an unbelievable 495-foot home run from Bryant, the longest home run in the Majors this season. The ball hit well up on the Cubs' new video board, the second time Bryant has hit that board this year. That 495-foot measurement is only where the ball hit the video board.

Bryant now has 23 home runs and 86 runs batted in. MLB.com's Greg Garno reports that Bryant's RBI total ties the Cubs' rookie record held by Hall of Famer Billy Williams (1959) and 2008 N.L. Rookie of the Year Geovany Soto (now with the Chicago White Sox). Bryant's 23 home runs also tie Soto's rookie record. The Cubs still have 27 games left this season, so expect Bryant to claim both records as his own very soon.

Justin Grimm (W: 3-4, 1.94 ERA) pitched the top of the sixth and benefited from Montero's grand slam. He walked one and allowed no hits in his one inning of work. Cubs starter Kyle Hendricks pitched five innings, allowing one earned run on three hits while walking two and striking out four. 

Rubby De La Rosa (L: 12-7, 4.49) left with two on and nobody out in the sixth. He was charged with three earned runs in five official innings. He walked two and struck out six. 

With the win, the Cubs maintain their 7.5-game lead over the Washington Nationals, who also won Sunday, for the second N.L. Wild Card position. The Cubs trail the Pittsburgh Pirates by 2.5 games for the top wild card spot and the division-leading St. Louis Cardinals by nine games. Both situations pend the outcome of the Pirates-at-Cardinals game Sunday night.

The Cubs travel to St. Louis Monday to begin a three-game series with the Cardinals, and they will host the Cardinals from September 18-20. St. Louis has won 9 of 13 meetings this season. The Cubs also have seven games remaining with the Pirates; the Cubs are 7-5 against Pittsburgh.

Arizona returns home Monday to host the San Francisco Giants for three games.