WASHINGTON -- Tyson Ross and Gio Gonzalez were teammates when the two played with the Oakland A's in 2010-11.

So bragging rights were at stake when the two faced each other on Wednesday night in the middle game of a three-game series. Ross got the best of Gonzalez on the mound and at the plate as the San Diego Padres withstood a three-run rally in the seventh inning to beat the Washington Nationals 6-5.

Ross got the win and also had two hits, including one against Gonzalez.

"It got a little lucky. We were talking trash," Ross said with a grin about his single in the third inning. "I got lucky."

Justin Upton hit two home runs and had three RBIs and Ross pitched into the seventh inning as the Padres dampened Washington's playoff hopes.

The Nationals (63-62), who had won three in a row, are now 6 1/2 games behind the National League East-leading New York Mets, who beat the Philadelphia Phillies soon after Washington's game ended.

One night after Washington's Stephen Strasburg was superb on the mound, Gonzalez had another poor outing.

"I was pounding the zone," said Gonzalez, who couldn't point to one certain thing that hampered his effort.

Gonzalez allowed the leadoff hitter to reach on a single in the first four innings.

"You still have to pitch whether the windup or the stretch," Gonzalez said. "It was good to see a familiar face and a good friend. (Ross) keeps his composure."

The Nationals will have to do the same to catch the Mets, but the defending East champions have lost eight of their last nine games decided by one or two runs.

San Diego (62-64), which has won eight of its last 11, started the day 7 1/2 games behind the first-place Los Angeles Dodgers in the NL West.

Washington cut San Diego's lead to 6-5 in the seventh as second baseman Anthony Rendon walked with the bases loaded and right fielder Bryce Harper had a two-run single, his second hit of the game. But third baseman Yunel Escobar hit into a double play on a 3-0 pitch to end the inning against reliever Mark Rzepczynski.

"A quality (double play) turn by our guys," said Padres interim manager Pat Murphy, who said he saw Escobar get the OK from the Washington bench to swing away. "We escaped trouble. Game-changing play. It really worked out."

Joaquin Benoit worked a perfect eighth for the Padres and closer Craig Kimbrel pitched a scoreless ninth for his 36th save as left fielder Jayson Werth grounded out to end it.

Upton, a Virginia native, had hit his second homer -- a solo shot -- in the seventh against reliever Doug Fister to give the Padres a 6-2 lead. Upton has 22 homers this year but just seven on the road.

"The splits at home and on the road are different," Murphy said. "He did it tonight. He is approaching his numbers" for an average season.

The Nationals had cut the lead to 5-2 against Ross in the sixth after first baseman Ryan Zimmerman had a sacrifice fly. But Ross struck out shortstop Ian Desmond with two runners on base to end the threat.

Ross (9-9) gave up four runs in 6 1/3 innings with nine strikeouts.

"He pitched great tonight," Murphy said. "He was sensational. We didn't play great behind him, for sure. He had a couple of knocks, too, which is great."

The losing pitcher was Gonzalez (9-7), who has lost his last three starts while giving up 20 hits in 12 1/3 innings during that span.

San Diego catcher Austin Hedges also had two hits, and Washington center fielder Denard Span had two doubles in his second game since coming off the disabled list.

The Padres scored four runs (three earned) in the third against Gonzalez.

Ross led off with a single and with one out Melvin Upton Jr. reached on an error by Escobar. Right fielder Matt Kemp followed with a two-run double up the right-center alley and Justin Upton followed with a screaming two-run homer into the San Diego bullpen in left for a 4-0 lead.

Padres third baseman Yangervis Solarte made it 5-0 in the fourth when his pop fly in foul territory caught by Ryan Zimmerman allowed Hedges to score from third.

The Nationals manufactured a run in the fourth as Harper drew a walk, took second on a groundout, stole third and scored when Zimmerman grounded out to make it 5-1.

Ross entered the game having allowed just five homers in 151 2/3 innings, good for 0.30 homers per nine innings, the best mark in the majors. The second-best mark belonged to Gonzalez (0.41).

Gonzalez has now allowed 16 runs (14 earned) in his last three starts after eight games in a row in which he allowed two runs or less.

NOTES: Nationals RHP Joe Ross (4-5, 3.56 ERA), Tyson's younger brother, will start Thursday against Padres RHP Andrew Cashner (5-12, 4.03 ERA). ... Padres OF Matt Kemp had his 15-game hitting streak end Tuesday. It was the longest streak for a Padre since Will Venable in 2013. Kemp had 30 go-ahead RBIs through Tuesday to lead the majors. ... Nationals RF Bryce Harper entered Wednesday with 31 homers and 30 doubles. He led the National League in on-base average (.454), slugging (.639), wins above replacement (7.2) and homers through Tuesday.