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Ian Desmond roped the go-ahead two-run double in the sixth inning and 19-year-old phenom Bryce Harper crushed his first major league home run as the Washington Nationals topped the San Diego Padres, 8-5, in the opener of a brief two-game series on Monday.

Desmond finished with three hits, Chad Tracy and Xavier Nady each had solo homers, Ryan Zimmerman added an RBI single and Adam LaRoche chipped in with an RBI groundout for the Nats, who bounced back from a 9-6 loss to the Cincinnati Reds on Sunday for their fourth win in five games.

Harper's first career longball came in the third inning off Padres starter Tim Stauffer. Harper showed patience during the at-bat by taking the first two pitches for balls, and after a called strike, he got a hanging slider and crushed it deep to center field, over the wall and onto the lawn.

He circled the bases slowly and came out for a curtain call after crossing the plate to give the Nats a 4-1 lead at the time.

"I was trying to go up there and get a knock. That's all I was worried about. I was trying to get something I could drive and go out of the ballpark," said Harper.

Craig Stammen (3-0) earned the win with two scoreless innings in relief of starter Ross Detwiler, and Sean Burnett got struggling closer Henry Rodriguez out of a bases-loaded jam in the ninth to record his first save of the year

Orlando Hudson smacked a two-run single, and Stauffer and Chase Headley each knocked in a run for the Padres, who have lost four of their last five. Miles Mikolas (0-1) was charged with the loss after allowing Desmond's hit.

Trailing 5-4 after five innings, Washington grabbed the lead for good in the sixth. Rick Ankiel drew a leadoff walk from Mikolas and Jesus Flores followed with a single, which allowed Ankiel to go first-to-third. Stammen put down a sacrifice bunt to move Flores into scoring position and Desmond followed by blasting a fastball high off the right field scoreboard to plate both runners for a 6-5 advantage.

Tracy, as a pinch-hitter, and Nady both smashed home runs in the eighth to give the Nationals some much-needed breathing room.

Will Venable worked a leadoff walk in the ninth and after James Darnell popped out, Cameron Maybin and Chris Denorfia walked to load the bases with one down. Nationals manager Davey Johnson summoned Burnett from the bullpen and he got Jesus Guzman to ground into a game-ending 1-2-3 double play.

Earlier, The Nats opened the scoring in their first at-bat. Desmond led off the inning by reaching on a poor throw by Headley and advanced to second. He then moved to third on a flyout by Roger Bernadina and crossed the plate with the game's first run on a groundout by LaRoche.

But the Padres got the run right back in the second. Yonder Alonso cracked a double to begin the frame and came home with the tying run three batters later when Hudson lofted a deep fly ball to right that hit off the heel of Harper's glove.

Washington took a 4-1 lead in the third, Desmond again got things started with a single up the middle and Bernadina followed with a base hit. Zimmerman then came through with a base hit to left to score Desmond for the first run of the inning. Bernadina advanced to third on a double-play groundout by LaRoche and scored when Headley was unable to handle a pickoff throw to third from catcher Nick Hundley.

Harper then followed with his milestone home run.

San Diego got all three runs back in the fourth. Alonso ripped a single to start things and Headley followed with a double off the wall in center to put runners on second and third. Hudson then cracked a base hit back through the box to bring home both runners for a 4-3 game. Jason Bartlett walked and Hudson stole third on the play to put men on the corners with one down. Stauffer dropped down a perfect safety-squeeze up the first base line which allowed Hudson to score for a tie game.

The Padres took a 5-4 lead in the fifth when Guzman ripped a one-out double into the right-center field gap, moved to third on a groundout by Alonso and trotted home on a single by Headley.

"Unfortunately, I put us in a little bit of a hole," Stauffer said. "It was a battle from the get-go. Obviously, there are some pitches I'd like to have back."

Game Notes

Alonso has hit safely in 15 of his last 17 games...San Diego fell to 4-17 when allowing the first run this season...Nationals catcher Sandy Leon left the game in the fourth inning after getting bowled over by Headley on a play at the plate...Both teams went 2-for-11 with runners in scoring position and stranded seven on base.