PHOENIX -- Troy Glaus capitalized on one of the few chances Arizona had against Tony Armas Jr.
Glaus hit a three-run homer on a 3-0 pitch to bring Arizona from behind, and the Diamondbacks held on to snap their 10-game losing streak against the Washington franchise by beating the Nationals 3-2.
"I was trying to get ahead in the count, work the count and get a pitch to hit," Glaus said. "Fortunately, it went to 3-0 and they gave me the green light, so I looked for something to drive."
His NL-leading 10th homer was only the second hit allowed by Armas, who made his 2005 debut after coming off the disabled list the day before. The 432-foot shot onto the concourse gave the Diamondbacks a 3-2 lead in the sixth inning.
"That's a huge home run for us," Arizona manager Bob Melvin said. "We don't have anything to show for anything, basically. We get a couple guys on, he hits a three-run homer. I think we get outhit 10-3 or something like that. Hopefully that's something that will break open the floodgates."
Glaus had two of the Diamondbacks' three hits.
Armas (0-1), winless in eight starts since beating Florida 2-1 on July 23, allowed all three runs, along with three walks, in 5 2/3 innings.
Brad Wilkerson drove in two runs with his 13th double for the Nationals, who twice failed to score after loading the bases against starter Shawn Estes (3-3). They stranded 13 runners, matching a season high, and left the bases loaded three times in all.
Mike Koplove walked two in the eighth, but Brandon Lyon escaped a bases-loaded jam by striking out Jamey Carroll after hitting Wilkerson with a pitch. Lyon then pitched a scoreless ninth for his 12th save, ending Arizona's three-game skid.
"It was just a big win for our team, especially, you know, being down, making a comeback and then having the bullpen come in and just shut the door," Lyon said.
The 10 consecutive wins over the Diamondbacks were the Washington franchise's longest streak against any team since the Montreal Expos won a record 15 straight against San Diego from 1993-95.
Armas, who had made just 21 starts over the two previous seasons due to back and shoulder problems, was on the disabled list from March 28 until Monday after straining his groin in an exhibition game against the New York Mets.
His last big league appearance was Sept. 12 in Atlanta.
"Armas was great," Nationals manager Frank Robinson said. "After the first inning, outstanding. He was in the strike zone, breaking ball was sharp, control was very good."
Estes snapped a two-game skid by allowing two runs and eight hits in six innings. He walked none and had a season-high eight strikeouts.
"It was one of those nights where I was able to make the big pitch when I needed to. That's because I had my stuff," Estes said. "If I don't have my stuff, there were situations where they just needed to put the ball in play to score."
Estes was perfect through three perfect innings. Meanwhile, Armas walked his first batter and then retired the next 11 before Glaus doubled in the fourth. Estes gave up his first three hits in the fourth, singles by Wilkerson, Carroll and Nick Johnson to load the bases.
He got Jeffrey Hammonds on a called third strike for the final out of the inning.
But in the fifth, Carlos Baerga, released by the Diamondbacks after last season, beat out an infield hit, Brian Schneider doubled and Wilkerson doubled into the gap to make it 2-0.
In the sixth, Vinny Castilla and Johnson singled, and Estes loaded the bases again by plunking Baerga with one out. But he stranded the runners again when Schneider popped up and Armas lined out.
Walks caught up with Armas in Arizona's half. He walked pinch-hitter Quinton McCracken to lead off and Luis Gonzalez with two out before Glaus' homer.
"I'm not worried about Gonzalez," Armas said. "I think it was McCracken that you've got to go after. I made some pitches and he didn't go for them."
Phoenix Suns C Amare Stoudemire, seated in the front row behind the backstop, got a big hand from the crowd. ... The Nationals are 5-3 on a nine-game road trip and could still take three straight road series against West Coast teams for the first time since 1989 by beating Arizona on Wednesday. ... Washington played its ninth consecutive error-free game, one short of the franchise record set in 1977 and matched last season.