DENVER – Charlie Blackmon hit his first career leadoff homer and Tyler Chatwood pitched seven strong innings Tuesday night, lifting the Colorado Rockies to an 8-3 victory against the Boston Red Sox.

John Lackey (10-13) of the Red Sox struggled on the road again, allowing four runs and six hits in six innings. He is 1-5 away from Fenway Park since the All-Star break.

Lackey also gave up solo homers to Troy Tulowitzki and Corey Dickerson.

Chatwood (8-5) shut down a potent Red Sox lineup, giving up one unearned run and three hits before being pulled for a pinch hitter with a 4-1 lead in the seventh.

The Rockies went on to score four times that inning with D.J. LeMahieu and Michael Cuddyer delivering two-run singles.

Cuddyer finished 2 for 4 with a double to raise his average to an NL-best .335.

With the AL East title wrapped up, the Red Sox are focused on securing the best record in the league. They held a one-game lead over Oakland heading into the night.

Manager John Farrell also is using these last few games to figure out his final postseason roster spots. Farrell said there are a couple up for grabs.

David Ortiz played first base instead of Mike Napoli without the use of a designated hitter. Ortiz showed off his glove, snaring a scorching liner from Dickerson to end the sixth.

The only mistake Chatwood made wasn’t on the mound but covering first base in the seventh. With two outs and Will Middlebrooks on second, Todd Helton made a diving stop on Jackie Bradley Jr.’s grounder and flipped it to Chatwood, who dropped the ball before stepping on the base.

Chatwood scooped it up and threw wide to the plate and into the Red Sox dugout, allowing Middlebrooks to score. Chatwood was charged with two errors on the play and Bradley advanced to third.

But Chatwood escaped more damage when his wild pitch bounced off the wall behind home plate, allowing catcher Jordan Pacheco to quickly field the ball and flick it to Chatwood, who tagged out Bradley, keeping the score 4-1.

Saltalamacchia hit a two-run homer in the ninth after Ortiz singled.

Blackmon, the reigning NL player of the week, began the game with a homer to right on a fastball from Lackey. Cuddyer soon followed with a double and scored on Helton’s single.

Helton clapped his hands after his hit as the crowd roared. The first baseman will retire at the end of the season after 17 years with the Rockies.