Updated

Ryan Zimmerman stroked one of Washington's four solo home runs to back a strong start from Tanner Roark, as the Nationals completed a four-game sweep of the New York Mets with a 7-2 triumph on Thursday at Citi Field.

Adam LaRoche, Wilson Ramos and Anthony Rendon each added a solo shot, while Roark (6-0) held the Mets to two runs on six hits over six solid frames in his second career start to help the Nationals notch their sixth straight victory.

Washington center fielder Denard Span doubled and scored a run in the eighth to extend his hitting streak to 23 games.

"Span is the catalyst," Washington manager Davey Johnson said of his center fielder. "Your leadoff guys are always the catalyst."

Aaron Harang (0-1), making his Mets debut after signing with the club on Sept. 1, struck out 10 over six innings of work, but was done in by the longball, with three of his four hits given up going for home runs.

"We didn't keep the ball in the ballpark," Mets manager Terry Collins said. "That's tough for us to catch up when we don't hit home runs."

Daniel Murphy and Anthony Recker each knocked in a run for the Mets, who have lost four straight games.

Zimmerman homered with one out in the first to give Washington the lead, but New York answered in the home half of the frame when Murphy doubled home Eric Young, who led off the inning with an infield single.

Washington regained the lead in the second when LaRoche scorched a one-out blast into left-center field. The play was originally ruled a double, but after video review, the umpires overturned the call, giving the Nats a 2-1 edge.

New York evened the score on Recker's RBI single to left in the fourth, but Ramos led off the next half-inning with a drive over the wall in left-center to put the Nationals back on top.

Washington tacked on a run in the seventh when LaRoche laced a leadoff double, moved to third on a groundout, and scored on Rendon's sacrifice fly to center to make it 4-2.

After the Mets left runners on second and third in the home half, the Nationals extended their cushion in the eighth when Span and Zimmerman stroked back-to-back doubles to push the lead to 5-2.

Zimmerman scored later in the frame on Ian Desmond's groundout before Rendon ripped a one-out blast to left in the ninth to account for the final margin.

Game Notes

Zimmerman homered for the second consecutive game and has gone deep eight times in 11 games during the month of September ... Roark started the season in the bullpen before transitioning to the rotation on Sept. 7, when he tossed six scoreless innings of four-hit ball in a 9-2 triumph at Miami ... Harang went 5-11 over 22 starts with the Mariners before being released on Aug. 31.