Austin Kearns then hit a hard grounder that went past third baseman Mark Reynolds for an error. Both Lopez and Willie Harris, pinch-running for Casto, scored on the play. It looked like Guzman had a chance to go to third, but he collided with second baseman Orlando Hudson while circling the bases, and was sent back to second for interference.
Manager Manny Acta went out to talk to second-base umpire Angel Hernandez about the play, but both ended up agreeing that Hudson did not prevent Guzman from going to third.
Even Guzman didn't think Hudson interfered on the play. Guzman, in fact, said he was the one who initiated contacted with Hudson.
"I had to stop," Guzman said. "I made a little bit of contact, so that's not his fault."
After Dmitri Young flied out to center fielder Chris Young and Jesus Flores struck out, Wily Mo Pena hit a ground ball to Reynolds, who bobbled the ball and was charged with his second error of the inning.
The Nationals had the bases loaded again when Roger Bernadina came to the plate. He battled Lyon for nine pitches, but grounded out to Hudson to end the inning.
"At that moment, I was focused on getting a hit up the middle," Bernadina said. "I was ready for it. ... He threw me a good pitch and I rolled over on it. I have to take my hat off to him."
Without a doubt, Jon Rauch is the Nationals' best pitcher. Entering Thursday's action, he had 16 saves and a 1.56 ERA as the team's closer.
But on Thursday, Rauch wasn't at his best, and while he was able to get two quick outs in the top of the 10th inning, he quickly fell apart. After Conor Jackson singled, Chad Tracy followed and doubled to left-center field to score Jackson. Reynolds made up for his two ninth-inning errors by following with an RBI double. Miguel Montero then singled to drive in Reynolds.
"Obviously, I didn't perform the way I wanted to," Rauch said. "Tonight was a real poor night of execution of two-strike pitches. It seems like I would get ahead of guys and I would give them way too good of a pitch to hit. That lineup is going to come alive. They have some real good hitters in that lineup. You tip your hat to them when they get their hits, but I made it too easy for them tonight."
Down three in the tenth, the Nationals came back again to tie the score at 5. With Tony Pena on the mound and one out, Willie Harris singled to drive in Pete Orr, who arrived at the ballpark in the ninth inning after being recalled from Triple-A Columbus.
Guzman followed and singled to left field to put runners on first and second. Kearns then doubled down the left-field line to drive in two runs and tie game.
The Nationals had a chance to win the game, but right-hander Chad Qualls shut them down. Kearns was on third with one out, and after Young was intentionally walked, Flores hit a grounder to shortstop Augie Ojeda, who threw Kearns out at the plate. Wily Mo Pena grounded out to end the inning.
With Washington reliever Luis Ayala on the mound and one out in the 11th, Stephen Drew doubled down the left-field line to drive in Ojeda. Two batters later, Tracy drove in Hudson to make it a two-run game.
Although the Nationals have now lost seven out of their last eight games and dropped their record to 35-58, Acta said he was pleased with the way the team battled back.
"It would have been tougher if we were shut out, 2-0 -- we made two great comebacks on those guys," Acta said. "It's tougher to lose anyway. It would have been tougher to be shut out again."
And what can Nationals right-hander Jason Bergmann do to win a ballgame? He pitched his fifth consecutive quality start, but he ended up with a no-decision. He hasn't won a game since May 15.
Bergmann pitched seven innings and gave up two runs on six hits.
Like teammate John Lannan the day before, Bergmann was politically correct when talking about himself and the team.
"We are not winning," Bergmann said. "My job is only part of the game. There's two parts of the game. I think everybody in this clubhouse would say, 'We would like to be winning more.' I think we have been in a position to win. It just hasn't fallen our way."