Carlos Maldonado and Ryan Zimmerman hit three-run homers off Chris Sampson, long after Oswalt was ejected, and Washington put together the highest scoring inning in Nationals' history for a 14-4 win over the Astros on Monday.
After the game, the Nationals announced on Twitter that their prized prospect Stephen Strasburg will make his big league debut June 8 against Pittsburgh.
Zimmerman and Adam Dunn drove in four runs apiece and both chipped in during a nine-run seventh, the team's biggest inning since relocating from Montreal before the 2005 season.
"It was kind of a snowball effect," said Josh Willingham, who went 2 for 3 with an RBI and a run scored. "Even some balls we weren't hitting well were falling, so it was a good day for everybody at the plate. You need a game like that every now and then."
Rookie Luis Atilano (5-1) allowed three earned runs on six hits in 6 2/3 innings, his longest outing of the season. The Nationals came in with the fifth lowest run total in the NL (216), but Zimmerman thinks they're capable of stringing together more big innings and moving into their division race.
"As good as we've been, we can do a lot better," Zimmerman said. "It's exciting. If we can get rolling and scoring some runs, the way our pitchers have been throwing, we'll be a good team."
Dunn broke a 1-all tie with a three-run double off Oswalt in the third. Oswalt (3-7) gave up more than three earned runs in a start for the first time this year.
And then Oswalt lost his cool after missing the strike zone with a 2-2 pitch to Willingham. He turned his head toward the first base line and yelled something. Oswalt said he was chastising himself, not snapping at home plate umpire Bill Hohn, but Hohn took off his mask and barked back to the mound.
"I have never seen that before," Oswalt said. "I was actually upset that I threw a ball that ended up a little bit off the plate. I was actually talking to myself on the mound and I wasn't even looking his way.
"When I turned around, he was pointing at me saying something like, 'Keep your mouth shut,' or something," Oswalt said. "I couldn't really tell you what he said. I told him that I wasn't talking to him, and he kept on talking."
Oswalt has acknowledged his frustration with the Astros' dismal start and about two weeks ago, his agent asked the Astros to try and deal him. Oswalt said he wasn't trying to earn an ejection.
"If I was," he said, "I would have said a lot more than that."
Gustavo Chacin, a left-hander recalled from the minors on Friday, replaced Oswalt. In the bottom of the third, Chacin homered down the right field line, his first hit in eight career at-bats.
The Nationals tacked on another run in the fifth, then blew it open in the seventh.
Jeff Fulchino relieved Chacin and gave up a leadoff walk to Nyjer Morgan. Zimmerman doubled to center and Morgan scored on Dunn's infield single. Willingham walked and Desmond drove in two with a single for an 8-2 lead.
Washington was just getting started.
Sampson relieved Fulchino, and Maldonado homered off the left-field foul pole, setting a career high for RBI in a game with one swing. Maldonado's contract was just purchased by Washington last week, after Ivan Rodriguez was injured.
Cristian Guzman and Morgan singled to keep the inning alive, and Zimmerman homered to right for a 14-2 lead. Washington reached its highest run total since a 14-6 win in Colorado on May 13.
"We had good at-bats, worked the count and got some timely hits," Zimmerman said. "It was nice to score some runs and have an easy one."
Houston scored two runs off Altilano in the bottom of the seventh, and Tyler Walker relieved.
- Oswalt was ejected for the first time since getting tossed twice in 2004. Hohn ejected him once that season, for hitting Chicago Cubs' C Michael Barrett with a pitch.
- Washington manager Jim Riggleman moved regular leadoff man Morgan to the No. 2 spot in the lineup. Morgan came in hitting .202 in May (20 of 99). "He's not been getting on base leading off, so really just trying to get him a different feel," Riggleman said.
- Brian Moehler (0-2, 7.29 ERA) will start Thursday's series finale in place of Bud Norris, who's on the disabled list with bursitis and right biceps tendinitis.
- Two fans ran across the outfield and were apprehended by security personnel at different points in the game. The first fan came out of the right-field stands in the seventh and climbed over the center-field wall. The next fan ran across the outfield from the opposite side of the field in the eighth.