WASHINGTON -- Ian Desmond had to wait nearly four minutes on third base Wednesday night while his potential go-ahead home run was reviewed.
"I was just wondering what I was going to do if they messed it up," he said, "and luckily they didn't."
After the replay review, Desmond's solo homer provided the go-ahead run as the Washington Nationals rallied from a three-run deficit for 4-3 win over the Colorado Rockies, sweeping the three-game series.
Right-hander Matt Belisle (2-4) came on to face Desmond with one out in the seventh. Desmond's hit appeared to bounce off the top of the wall in right center, then off the railing in front of the first row and onto the field.
"The way it bounced back hard like that I kind of assumed it was over, and the way that (center fielder Drew) Stubbs kind of just didn't go after it made it a little bit easier," he said. "But at that point I was like `I'm going to get a triple,' so yes I thought it was gone, but I wasn't 100 percent sure."
After a review that took 3:42, Desmond had his 15th homer.
Jayson Werth also homered for Washington, which has won a season-high five straight.
Washington's Doug Fister (7-2) was hit hard early and allowed three runs on seven hits over seven innings.
"Constant battle all night," he said. "Biggest thing was making sure the ball got down in the zone."
Michael McKenry hit a three-run homer for Colorado, which has lost 14 of 16 and finished its road trip 1-6.
Rockies rookie left-hander Tyler Matzek went 6 1/3 innings, allowing three runs on six hits in his fifth start. He threw 95 pitches, striking out six and walking one.
Matzek struck out the final three batters he faced -- the last one being left-handed Bryce Harper -- before manager Walt Weiss brought in Belisle to face the right-handed Desmond.
"I think (Matzek) got stronger as the game went on, but he was in uncharted territory," Weiss said. "He's a young guy that probably hasn't thrown more than 90, 95 pitches in the game."
The Rockies took 3-0 lead in the second.
Colorado hit the ball hard off Fister, who finished with five strikeouts and no walks while improving to 5-0 this season at Nationals Park.
"There was a lot of strong contact tonight but guys made some great plays," Fister said.
Washington tied it in the fourth.
After Anthony Rendon singled and stole second, Matzek fell behind Werth 3-1. He left a fastball up and Werth sent it just over the center field fence for his seventh homer.
"Had a base open, 3-1 to a big hitter, that was a stupid pitch," Matzek said.
Harper followed with a bloop double to short left, went to third on a wild pitch, and scored on Desmond's single.
"I don't think we ever think we're out of it," Williams said. "We think that we have a chance at any time, especially three down."
With the exception of Jose Lobaton spelling catcher Wilson Ramos, Williams used the same lineup for the third straight game since Harper returned, with Harper in left, Ryan at third and Rendon at second.
Colorado turned a highlight-reel double-play in the first.
With no outs, second baseman DJ LeMahieu made a sliding stop of Rendon's grounder behind second base and flipped it with his glove hand to shortstop Tulowitzki at second. Tulowitzki barehanded the toss facing center field, spun around and fired to first in time to get Rendon.
The Rockies acquired RH Jair Jurrjens from the Reds for minor league first baseman Harold Riggins. Jurrjens, who was pitching at Triple-A Louisville, has a 53-37 record with a 3.63 ERA in seven major league seasons. ... An MRI on RH Jhoulys Chacin's shoulder did not indicate a quick return from the DL. "It looks like he has some (rotator) cuff inflammation and we need to sit down with the medical staff and figure out a plan of attack," manager Walt Weiss said. ... Williams said Harper, who has hit sixth since returning from the DL on Monday, will eventually move up. "Does he hit two for us, three for us, does he hit four? Yes. Maybe not today, but he will." ... The Nationals are off Thursday, while Colorado hosts the Dodgers with LH Franklin Morales (4-4, 5.75) opposing RH Zack Greinke (10-4, 2.78).