DENVER

John Lackey was originally going to throw an inning simply to stay sharp.

That plan was changed to a full-fledged start, to keep in rhythm.

Only, this wasn’t exactly the outing he was looking for with the postseason drawing near.

Lackey allowed three solo homers, including one to Charlie Blackmon, the first batter he faced, as the Boston Red Sox fell to the Colorado Rockies 8-3 on Tuesday night.

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

Lackey also surrendered solo homers to Troy Tulowitzki and Corey Dickerson.

Tyler Chatwood (8-5) shut down a potent Red Sox lineup as he gave 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 to seal the win, with DJ LeMahieu and Michael Cuddyer delivering two-run singles.

Cuddyer finished the night 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 now focused on securing the best record in the league. They maintain a one-game lead over Oakland after the Athletics lost 3-0 to the Los Angeles Angels.

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

Chatwood pitched carefully to the dangerous Ortiz, even intentionally walking him in first with a runner on second. The ploy worked as Jarrod Saltalamacchia grounded out.

Later, Ortiz hit a fly to the deepest part of the park, but Blackmon tracked it down.

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 quickly flipped it to Chatwood, who dropped the ball before stepping on the base.

Chatwood scooped it up and threw wide to home 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.

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.

Notes — Saltalamacchia hit a two-run homer in the ninth after Ortiz singled. … Red Sox center fielder Jacoby Ellsbury (right foot) may return to the lineup as soon as today.

• Who: Boston Red Sox at
Colorado Rockies.
• Where: Coors Field.
• When: 8:40 p.m. tonight.
• Starting pitchers: Boston
(Jake Peavy 11-5) vs. Colorado (Jhoulys Chacin 14-
9).
• TV: NESN.