With the Rockies down 1-0, Charlie Blackmon started the third-inning rally with a one-out triple and scored on a DJ LeMahieu double. LeMahieu should have been out trying to get to third on Nolan Arenado’s ground ball to short, but was safe thanks to a throwing error.
Back-to-back hits from Carlos Gonzalez and Mark Reynolds scored LeMahieu and Arenado, giving the Rockies a 3-1 lead. After Ian Desmond and Trevor Story reached, a three-run single from Ryan Hanigan extended the Rockies lead to 6-1.
The five-run lead allowed Rockies starter Antonio Senzatela to settle in. The rookie pitched six innings, allowing two runs on five hits, walking three and striking out four. He threw 99 pitches, 57 for strikes and tied Clayton Kershaw for the NL lead with his fifth win.
Colorado continued its offensive onslaught in the fourth, scoring three runs on four hits and a walk, chasing Cubs starter Jake Arrieta from the game in the process and taking a 9-2 lead.
Reynolds hit his team-leading 12th home run of the season to make it a 10-2 Rockies lead in the sixth, and the Cubs got a lone run against each of Chris Rusin and Chad Qualls for the 10-4 final.
The Rockies will look to sweep the doubleheader and win the series in the nightcap, which is scheduled for 6:40 p.m. Mountain time. Kyle Freeland and John Lackey are the scheduled starters.