WASHINGTON -- After first baseman Ryan Zimmerman caught the last out on a double play grounder, he walked across the diamond and gave a high five to third baseman Yunel Escobar.

Zimmerman then held up the ball and looked towards home plate, as reliever Blake Treinen and catcher Wilson Ramos congratulated each other Tuesday night in the top of the ninth.

For the first time this season the Nationals were at full strength and for at least one night that translated into clutch hitting. Every Washington run was driven in with two outs, Stephen Strasburg allowed just two runs in six innings and Zimmerman hit a grand slam in an 8-3 win over the San Diego Padres.

"We have a lot of good players. To be able to see that is nice," Zimmerman said after the return of center fielder Denard Span, which gave the Nationals its eight top everyday players in the lineup for the first time all year. "Hopefully we can keep scoring runs for them (starters). Hopefully we can get some momentum and keep playing like we have been the last week or so."

The Nationals (63-61), who began the day 5 1/2 games back of the first-place New York Mets, won three in a row for the first time since July 11-17.

The Padres (61-64) lost for just the fourth time in the last 11 outings as interim manager Pat Murphy was ejected in the seventh after replays showed Washington right fielder Bryce Harper did not foul the ball off his foot the previous inning. Harper, who appeared to groundout, then walked and two batters later Zimmerman hit his slam -- with two outs.

"It's unfortunate because (the call) played a role," Murphy said. "The ball was almost at Yonder (Alonso) at first base when the call was made. Umpires miss calls, coaches miss calls."

Strasburg (8-6) won for the fourth time in five decisions and had his fourth strong outing in a row since coming off the disabled list earlier this month.

"I'm just going out there with the same game plan and trying to focus on hitting my spots and using all my pitches, and Willie's been calling great games, and the bats have been coming alive a little bit, so we need to keep that rolling," Strasburg said, giving credit to catcher Wilson Ramos.

He gave up only two hits and struck out seven with one walk and has allowed just four hits in his last 13 innings.

"He is getting ahead a lot (in the count). He is being aggressive attacking the zone," Zimmerman said of Strasburg.

Span, who missed the previous 40 games with back problems, was finally at the leadoff spot again and he drew a nice ovation when he stepped to the plate in the first. Even though he was hitless in four official at-bats, he drew a walk and helped drive up the pitch count of San Diego starter and loser James Shields (9-6).

Shields left the game after his 121st pitch -- when second baseman Anthony Rendon hit a comebacker off his leg and reached on an infield single in the sixth.

Later in the inning, first baseman Zimmerman hit his grand slam off reliever Bud Norris to give Washington an 8-2 lead. It was the 10th homer of the season for Zimmerman, who like Span, also missed 40 games this year on the disabled list.

"It was a slider ... a little off the plate. Obviously an ideal situation" being ahead in the count, Zimmerman said. "Just try not to do too much with it."

Said Murphy: "He hit a real good breaking ball."

Shields gave up five runs and eight hits in 5 2/3 innings.

San Diego starting shortstop Jedd Gyorko hit a solo homer -- his second of the game and 10th of the year- in the seventh to cut the lead to 8-3 off reliever Casey Janssen. It was the third multi-homer game of his career and first this season as he drove in all three San Diego runs.

Rendon, shortstop Ian Desmond and third baseman Yunel Escobar had two hits for the Nationals. Rendon and Escobar also scored twice.

San Diego first baseman Yonder Alonso had two hits.

Gyorko hit a two-run homer to left in the second off Strasburg to give San Diego a 2-0 lead.

Ramos lined a two-run, two-out homer just over the fence down the left-field line to tie the game in the second.

Washington grabbed a 3-2 lead in the third off starter Shields. Rendon singled and Escobar got another two-out hit -- a double -- to drive in Rendon.

The Nationals built the margin to 4-2 in the fifth as Desmond had a two-out double to score Harper, who led off the frame with a double of his own. Strasburg retired the last 15 batters he faced.

"His stuff was dominant," Murphy said. "He was dominant."

NOTES: Washington CF Denard Span was activated from the disabled list before Tuesday's game and batted leadoff against the Padres. He missed 40 games with back tightness and hit .412 in six minor league rehab games. ... RHP Tanner Roark (4-4, 4.54 ERA in 34 games, including six starts) was sent to Class A Potomac with the intention of building up his pitch count for possible starting duty in September, according to manager Matt Williams. ... San Diego RHP Tyson Ross (8-9, 3.32) will start Wednesday against Washington LHP Gio Gonzalez (9-6, 3.98). Ross is the older brother of Washington rookie RHP Joe Ross, who will start Thursday against San Diego. ... Washington will skip the turn of RHP Max Scherzer, who was on track to pitch Wednesday, in order to have him lined up to pitch in future series against the St. Louis Cardinals and the New York Mets. Scherzer is slated to start Friday against the Miami Marlins. ... San Diego LF Justin Upton, batting cleanup, turned 28 on Tuesday.