Updated

WASHINGTON (AP) Drew Storen yielded an eighth-inning grand slam to Carlos Gonzalez, and the Washington Nationals blew a four-run lead in a 5-4 loss to the Colorado Rockies on Friday night.

When Storen entered with six outs to go and the score 4-0, Washington appeared well on its way recording a second straight win for only the second time since the All-Star break. Everything changed during a rare ineffective performance by the Nationals' former closer, who lost his job when Jonathan Papelbon was obtained in a July 28 trade with Philadelphia.

With two outs and a runner on first, Jose Reyes and Nolan Arenado singled to load the bases for Gonzalez, who drove a 1-0 pitch into the Washington bullpen beyond the wall in right field. It was the first time in 15 appearances since June 24 that Storen (2-1) gave up a run.

Since June 1, Gonzalez leads the NL with 19 home runs. This one was particularly painful for the Nationals, who have lost six of eight to drop 2 1/2 games behind the first-place New York Mets in the NL East.

Washington wasted a strong outing by Jordan Zimmermann, who allowed one run, four hits and no walks in 6 2-3 innings.

Bryce Harper scored two runs, singled, walked twice and hit a run-scoring grounder for the Nationals. Washington scored in three different innings against Jorge De La Rosa, and Harper was in the middle of each uprising.

One swing by Gonzalez, however, undid the lead that Harper helped build. Washington was 46-3 when ahead after seven innings.

Arenado had three hits and scored twice for the last-place Rockies, who now have their first winning streak since the All-Star break.

Scott Oberg (3-2) pitched a scoreless seventh inning, John Axford worked the eighth and Tommy Kahnle got three outs for his first major league save.

De La Rosa gave up three earned runs and six hits in six innings. Colorado's career leader in wins (76) has earned only one of them since July 5.

Washington got an unearned run in the first inning. Danny Espinosa doubled, took third when left fielder Kyle Parker misplayed the ball and scored on a groundout by Harper, his first RBI in nine games.

Harper led off the fourth with a single and scored on a double by Ryan Zimmerman for a 2-0 lead.

The Nationals added two runs in the sixth. After Espinosa got an infield hit and Harper walked, Jayson Werth hit a sacrifice fly and Ian Desmond followed with an RBI double.

Colorado finally broke through against Zimmermann in the seventh, when Arenado led off with a double and scored on a two-out single by Ben Paulsen.

TRAINER'S ROOM

Nationals: INF Anthony Rendon was given the day off, a precaution after his recent return from a left quad strain. ''If we push him too hard it can flare up again,'' manager Matt Williams said.

ON DECK

Rockies: RHP Eddie Butler (3-8, 5.45 ERA) faces Washington for the first time on Saturday. He's 0-3 with an 8.41 ERA in four starts since May 30.

Nationals: Stephen Strasburg (5-5, 5.16 ERA) returns from the 15-day DL (oblique) to make his first start since July 4.