WASHINGTON -- The Washington Nationals were stunned. They just aren't used to teams coming back against them late in the game.

Washington's usually reliable bullpen failed to protect a two-run lead, and the result was a 4-3 loss to the Colorado Rockies on Sunday that will linger on the Nationals' minds until after the All-Star break.

To some, the defeat was a blip in an otherwise outstanding season. To others, it was a reminder that past performances mean nothing.

Up 3-1 entering the eighth inning, Washington couldn't finish off the last-place Rockies. The setback cost the Nationals a chance to hit the All-Star break with their best record since the team moved to Washington in 2005.

Nationals reliever Sean Burnett, who came in with a 1.42 ERA, gave up two runs in the eighth -- including a drive by pinch hitter Eric Young for his first homer since Sept. 8, 2009.

"Unfortunately, you can't get the ball and go out there tomorrow," Burnett said. "You have to wait a few days until the break's over. It's going to be nice to have these four days off and relax with the family, but you would like to go out on a better note than that."

Despite the loss, Washington finished the first half with an NL-best 49-34 record.

Tyler Clippard, who gave up the tiebreaking run in the ninth, said: "Any time it doesn't go your way it's frustrating, but we can't really hang our heads. We've been playing well as a team. We have the All-Star game to regroup for a great second half. ... I think we're all satisfied with where we are right now."

Young homered leading off the eighth and Dexter Fowler and Marco Scutaro singled to put runners on the corners with no outs. Mike Gonzalez came in and threw his first wild pitch of the year, allowing the tying run to score.

Colorado made it 4-3 against Clippard (2-3), who walked to the mound with a 1.78 ERA. Jordan Pacheco led off with a double to left, took third on a sacrifice and raced home on Clippard's first wild pitch of the season.

The collapse proved that Washington's bullpen isn't perfect, something to think about during the break.

"I look at it as good timing," Clippard said. "You don't ever want to get too comfortable or too confident out there, so this is a little check for ourselves."

Rex Brothers (4-2) worked the eighth and Rafael Betancourt got his 15th save, striking out pinch hitter Jesus Flores with two outs and runners at second and third.

Fowler had two singles for his fourth straight multihit game for the Rockies, who took two of three from the NL East-leading Nationals. Colorado also won the season series 4-3.

"I'm really proud of the way the club played in this series," manager Jim Tracy said. "To win this series, to win the season series against them, you look for little incremental things in relation to where we're at and where we're trying to get to, and you feel awfully good about the way we gutted that thing out today."

Ian Desmond homered and Adam LaRoche had two hits and scored a run for the Nationals.

"Everybody feels good, and they're looking for the break," manager Davey Johnson said. "They've battled hard. We've had a lot of close games. It's a good time for a break."

Washington starter Jordan Zimmermann gave up one run and three hits over seven innings. He left with a two-run lead, but the bullpen promptly gave it away.

Colorado's comeback enabled Jeremy Guthrie to avoid his ninth loss. Guthrie allowed two runs, six hits and a walk in six innings.

Desmond removed himself from the All-Star Game on Saturday with a strained left oblique, but the injury wasn't evident 24 hours later. His 17th home run, a two-run drive in the fourth inning, gave Washington a 2-1 lead. Over his last 13 games, Desmond is 21 for 51 (.412) with 14 extra-base hits, including six homers, and 15 RBIs.

Early on, both teams squandered chances to take control.

The Rockies loaded the bases with no outs in the second inning but scored only one run, on a sacrifice fly by former Nationals catcher Wil Nieves.

Fowler drew a leadoff walk in the third and advanced to third with one out but was stranded.

Washington got a runner in scoring position in each of the first three innings before breaking through in the fourth. LaRoche led off with a double and Desmond followed with a drive over the center-field wall on a 3-2 pitch.

A run-scoring single by Steve Lombardozzi made it 3-1 in the seventh.

Game notes
Depending on how Nationals pitchers Stephen Strasburg and Gio Gonzalez are used in the All-Star game, Johnson said his rotation for after the break would be Zimmermann, Gonzalez, Strasburg and Edwin Jackson. Johnson hopes to limit Strasburg's innings in the second half, which could be why he's being pushed back. ... Guthrie is winless since May 31. ... Washington stole six bases. ... Zimmermann has worked at least six innings in all 17 starts this season.