The Washington Nationals have been unable to gain any traction over the last month, and it's cost them control of the NL East.

They're hoping a three-game series with last-place Colorado can help them build momentum, particularly with Jordan Zimmermann looking to improve upon his already sparkling resume against the Rockies in Friday night's opener.

Washington (56-51) has won two of three following a four-game skid, scoring 13 runs in those victories after totaling nine during the losing streak. The Nationals are hoping Ian Desmond is ready to break out of his slump after homering and doubling in Thursday's 8-3 win over Arizona. Desmond had been batting .129 with 15 strikeouts over his previous eight games.

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Washington is 1 1/2 games behind the New York Mets in the NL East after leading them by 4 1/2 games - its largest advantage of the year - before dropping 15 of its last 25.

Zimmermann (8-7, 3.54 ERA) is 0-2 with a 5.09 ERA over his last four outings. He gave up three homers for the first time in two years during a span of five pitches Sunday against the Mets, accounting for the five runs he allowed over six innings in a 5-2 road loss.

He's 2-3 with a 4.76 ERA in eight games when giving up a home run, and 6-4 with a 2.92 mark in 14 other contests. The seven homers he's allowed in his last six starts are two more than he surrendered through his first 16 outings.

Zimmermann, however, is 5-0 with a 2.20 ERA in eight matchups with the Rockies, one of two teams he's unbeaten against in at least five starts. The right-hander has yielded only two home runs over 49 innings against Colorado, though both came in the last meeting, a 7-4 road win for the Nationals on July 22, 2014.

He has completed at least seven innings in four of his last five home starts, though he's won only once there in the last six with eight runs of support over 38 innings.

Colorado (45-61) defeated Seattle 7-5 in 11 innings Wednesday, earning just its sixth win in 18 games on Michael McKenry's two-run homer.

Carlos Gonzalez has nine home runs and three doubles - with one of each Wednesday - along with 20 RBIs in his last 14 games. He appears to have two factors working against him in this matchup - he's 2 for 13 with six strikeouts against Zimmermann and hit .146 with 23 strikeouts in his last 11 meetings with Washington.

The Rockies are seeking consecutive victories for the first time in more than three weeks behind Jorge De La Rosa (7-4, 4.87). He gave up six runs in back-to-back starts before bouncing back with a better showing Saturday at St. Louis, limiting the Cardinals to two runs over 6 2-3 innings in a 6-2 victory.

The left-hander owns a 5-2 record in eight career starts against the Nationals despite a mediocre 4.07 ERA. He finished one strikeout shy of a career high in the most recent one July 23, 2014, recording 11 while giving up one earned run over 7 1-3 innings of a 6-4 home victory.

Bryce Harper struck out in all three career at-bats against De La Rosa.

Washington outscored Colorado 36-19 in winning five of last year's six meetings.