DENVER, Sept. 9 (UPI) -- Troy Tulowitzki hit two homers Wednesday, one of them a three-run shot that helped boost the Colorado Rockies to a 9-2 whipping of Cincinnati.

The Rockies have won the first three games of the four-game series and have captured six straight overall to jump into playoff contention.

Colorado began the evening 4 1/2 games behind San Diego for the National League West lead and the Rockies stayed within 4 1/2 games of Atlanta in the wild-card race.

Cincinnati missed out on a chance to expand its lead in the NL Central and stayed six games in front of St. Louis. The Reds have lost four straight.

It was the second multi-homer game in Tulowitzki's career, the other coming June 23, 2009. His three-run blast in the third gave the Rockies a 5-1 advantage and he added a solo shot in the fifth.

Seth Smith hit a solo home run for Colorado in the fifth as part of a four-run inning.

Carlos Gonzalez had a single in the sixth to extend his hitting streak to 16 games in Colorado's ninth straight home win over the Reds.

Aaron Cook (6-8) lasted five-plus innings to get the win. He allowed a run on six hits before being knocked out of the game when he was hit on the leg by a line drive.

The loss went to Bronson Arroyo (14-10), who gave up seven runs on eight hits in 4 1/3 innings. He dropped his third straight start.