WASHINGTON -- The Colorado Rockies blasted Washington Nationals starter Erick Fedde in his major league debut Sunday, scoring seven runs off the right-hander en route to a 10-6 victory in the first game of a day-night doubleheader.

Third baseman Nolan Arenado and second baseman DJ LeMahieu had three hits and two RBIs apiece for the Rockies, who have taken the first two in the three-game series.

Colorado southpaw Kyle Freeland (11-7) pitched five innings to earn the victory, breaking a tie with teammate Antonio Senzatela for the most wins among major league rookies. Freeland has won his last three decisions and is 3-0 with a 2.02 ERA in his last four appearances.

Rockies closer Greg Holland entered with the bases loaded in the ninth and, after allowing Anthony Rendon's RBI single, got Howie Kendrick to ground into a double play to secure his 33rd save in 34 tries.

First baseman Ryan Zimmerman homered twice and drove in four runs for the Nationals, his fourth multi-homer game this season. Zimmerman has hit 24 homers this year.

Fedde, summoned from Triple-A Syracuse earlier in the day to take the injured Stephen Strasburg's place in the rotation, is one of the Nationals' top pitching prospects. But he allowed runs in three of his first four innings.

The Rockies loaded the bases to start the first, only for Fedde to induce a run-scoring double-play grounder from first baseman Gerardo Parra. Raimel Tapia then singled to right to drive in LeMahieu.

Fedde encountered similar difficulty his second time through the order. Charlie Blackmon singled to lead off the third and LeMahieu doubled him home. After Arenado's single, Parra hit into another double play that scored a run.

The Rockies added three more runs in the fourth, though only one was earned thanks to Washington shortstop Adrian Sanchez's error for interfering with baserunner Trevor Story. Ryan Hanigan, Blackmon and Arenado all delivered run-scoring singles in the inning.

Only one of Colorado's 10 hits off Fedde went for extra bases.

Freeland allowed four runs (three earned) and nine hits, yielding a solo homer to shortstop Wilmer Difo in the first inning and a three-run shot to first baseman Zimmerman in the fourth. He struck out four and did not yield a walk.

Zimmerman later hit a solo shot off reliever Pat Neshek in the seventh. He has 905 career RBIs, tied with Tim Wallach for the most in franchise history.

NOTES: Colorado placed LHP Jake McGee (mid-back strain) on the 10-day disabled list, retroactive to July 27. McGee is 0-1 with a 3.27 ERA in 43 appearances. ... To replace McGee on the active roster, the Rockies recalled LHP Zac Rosscup from Triple-A Albuquerque. Rosscup, who made three appearance for the Rockies earlier this season, has thrown 9 1/3 scoreless innings for Albuquerque. ... Colorado added RHP Carlos Estevez as its 26th man for the doubleheader. Estevez, who was optioned to Albuquerque on Saturday, is 4-0 with an 8.10 ERA in five stints with the Rockies this season. ... In addition to adding Fedde to the roster, Washington recalled C Pedro Severino from Triple-A Syracuse as its 26th man for Sunday's doubleheader. Severino was optioned to Syracuse on Saturday, and is 2-for-5 with an RBI in five games with the Nationals this season after singling as a pinch hitter in the fourth inning. ... Washington also released OF Chris Heisey, who was on the DL with a left groin strain, to open a spot on the 40-man roster for Fedde. Heisey hit .162 with a homer and five RBIs in 38 games this season. ... Nationals 2B Daniel Murphy was out of the lineup for the opener of the doubleheader, the first game he didn't start since July 14. Murphy pinch hit in the sixth and remained in the game. ... The teams were to complete the series Sunday night with a makeup of Friday's rainout. Jon Gray (3-1, 5.84 ERA) starts for Colorado, while Edwin Jackson (1-1, 3.75) gets the nod for Washington.