Colvin homered twice and drove in four runs in his first start since his call-up, Jhoulys Chacin won for the first time since April, and the Colorado Rockies beat the Washington Nationals 8-3 on Tuesday night.
"It's one thing to be here, but I know I can contribute and help this team win," said Colvin, who opened the season at Triple-A Colorado Springs after spending all of last year with the Rockies. "Games like tonight justify why I'm here, you know?"
Carlos Gonzalez hit a tiebreaking three-run homer in Colorado's five-run fifth inning, which was touched off by the first of Colvin's two two-run homers.
"Big night for Tyler," Rockies manager Walt Weiss said. "He's swung the bat really well since he's been back with us. He's got enough power to where he's always a threat to go deep, and he did twice tonight."
Chacin (4-3), who was struggling with flu-like symptoms the past couple of days, allowed two runs and seven hits in five innings. He ended a string of four straight no-decisions and three consecutive losses since his last win April 19.
In that game, he pitched into the seventh inning to beat the Arizona Diamondbacks only to be forced out by lower back tightness. He spent a couple of weeks on the disabled list and was dealing with illness in his latest outing.
"He was sick tonight, didn't feel good," Weiss said. "He went out there and he had to grind through that outing. But he battled, and I guess that's the best way to put it, he battled."
Chacin felt better after ending his long winless drought.
"It was a long stretch without winning a game, but it finally came," Chacin said. "Hopefully, this will start a winning streak."
Trailing 2-0, the Rockies got to Dan Haren (4-8) in the fifth, sending 10 men to the plate.
Wilin Rosario drew a leadoff walk, and Colvin, who made his Rockies debut Sunday as a defensive replacement, drove a 2-1 pitch into the right-field seats for his first home run.
Nolan Arenado grounded out before Gonzalez, who struck out in his two previous at-bats against Haren, smacked an 88 mph cutter the opposite way to put the Rockies in front with his 18th home run of the season.
"Things were going well, made a couple of mistakes and just couldn't keep the ball in the ballpark," Haren said. "Felt good the first couple of innings, but made a couple of mistakes."
Colvin put the Rockies up 7-3 when he connected for a two-run shot in the eighth off reliever Drew Storen. It was his fourth career multihomer game and first since last July 6, also against Washington. The Rockies added a final run on Arenado's bases-loaded double-play grounder.
Haren went five innings and allowed six of his eight hits in the fifth. He lost for the fifth time in the past six outings.
"I feel like I am letting the team down," Haren said. "It's not for a lack of effort, it's not for a lack of work and not for a lack of belief. I believe every time I step on the mound, I'm going to win, and I have to keep that feeling. I've been good for a long time. This is just a bump in the road."
However, the Nationals finished with eight hits, ending a season-high string of four consecutive games with double-digit hit totals.
Washington fell to 2-9 in its past 11 road games.
Nationals OF Bryce Harper will be evaluated in a week after getting a cortisone injection in his swollen left knee. He's also wearing a brace to ensure he rests the joint. ... RHP Stephen Strasburg, who's on the DL with a lat strain, threw a simulated game Tuesday, and manager Davey Johnson said he came out of it well. Strasburg is eligible to come off the DL on Sunday. ... Rockies reliever Edgmer Escalona was placed on the 15-day DL with right elbow inflammation, and LHP Josh Outman was recalled from Triple-A Colorado Springs. ... Michael Cuddyer (rib strain) was out of the Rockies' starting lineup for a fourth straight game but is said to be improving and could be back soon. ... Haren has worked a scoreless first inning in 12 of his 13 starts this season.