Gio Gonzalez ran his scoreless innings streak to 20 over three starts and the NL East-leading Washington Nationals beat the San Diego Padres 3-1 on Tuesday night on just four hits at spacious Petco Park.

Chad Tracy, pinch-hitting for Gonzalez, hit a two-run single with one out in the seventh to chase Clayton Richard.

San Diego, last in the NL West, was trying for its first three-game winning streak of the season after splitting a four-game series with Philadelphia.

Xavier Nady, who started his big league career with San Diego in 2000, started the winning rally with a double to the wall in left leading off the seventh. Wilson Ramos followed with a walk and both scored on Tracy's single to center.

That made a winner of Gonzalez (2-0), who allowed two singles in six innings, struck out six and walked two. Henry Rodriguez pitched the ninth for his fifth save in as many chances.

The Padres had only one runner reach second base against Gonzalez.

Washington's last four starters have combined to throw 22 scoreless innings.

The Padres scored an unearned run in the eighth and had runners on second and third with one out before Tyler Clippard retired pinch-hitter Mark Kotsay and Chris Denorfia.

Washington added a run in the ninth when Ramos reached on a three-base error on right fielder Will Venable and scored on pinch-hitter Rick Ankiel's single.

Richard (1-2) allowed two runs and three hits in 6 1-3 innings, struck out six and walked five.

Padres manager Bud Black was ejected in the sixth for arguing a balk call against Richard. Black went out for a mound visit and began jawing at umpire Lance Barrett when he came out to break it up. The two yapped as they walked toward the plate before Barrett tossed Black.

NOTES: Nationals manager Davey Johnson said 3B Ryan Zimmerman was going to have an MRI on his right shoulder. Zimmerman missed his second straight start with what has been described as inflammation. Zimmerman had said he expected to return Tuesday. The Nationals were rained out Sunday and were off Monday. ... Padres RHP Tim Stauffer, who started the season on the DL with a strained elbow, pitched a simulated game on Tuesday and is scheduled to throw a side session on Thursday. If he feels OK, he'll probably make a rehab start at Class A Lake Elsinore on Sunday. ... LF Carlos Quentin, who began the season on the DL after having knee surgery, hit during the simulated game. Black said Quentin still has to run at full speed and be able to slide before he can be sent on a rehab assignment. That could be in a week to 10 days. ... RHP Stephen Strasburg hoped to start for the Nationals against his hometown Padres but the rotation didn't fall that way. Strasburg pitched twice at Petco Park while with San Diego State. "It's huge," Strasburg said. He remembers closing a game against Michigan as a freshman when a Wolverines batter hit a ball he thought would be a homer to straightaway center. "Our center fielder caught it in the middle of center field. It's a big park." ... Strasburg is scheduled to start Saturday at Los Angeles. ... San Diego SS Jason Bartlett and Venable each committed their fifth error, tied for the team lead. San Diego has committed 21 errors in 18 games.