ST. LOUIS — A rare, comical moment unfolded in the first inning of the Washington Nationals-St. Louis Cardinals game Saturday night at Busch Stadium.

The Nationals, who won 6-4 in 10 innings, had the bases loaded with one out against Kyle Lohse when Michael Morse lined a ball over the fence in right.

First-base umpire Chris Guccione, however, did not rule it a home run. Instead, Bryce Harper scored from third, and the Nationals wound up with Ryan Zimmerman and Adam LaRoche a few feet apart between second and third.

Morse rounded first, then retreated when he saw LaRoche at second and Zimmerman moving toward third.

Cardinals second baseman Skip Schumaker took right fielder Carlos Beltran's relay throw and chased down Morse, applying a tag before Morse slid back into first.

Umpires promptly went under the stands to review the play. They returned a couple of minutes later, and crew chief Jeff Nelson indicated that Morse's drive was over the fence for a grand slam.

But the craziness was just beginning.

After the umpires overturned the call, the runners, with the exception of Harper, had remained on the bases while the review was held. They began to jog home.

However, all were sent back to their respective bases by the umpiring crew --Harper to third, Zimmerman to second and LaRoche to first. Morse then returned to the plate and simulated a swing, sans bat, in effect recreating the grand slam that made it 4-0.

"I wasn't sure what to do, so I ran back and touched all the bases," Morse said. "Then I got to first, and they're like, 'Go back to the batter's box.' I'm like, 'What do you want me to do?' So I look over to the dugout, everybody's telling me to swing. I'm like, 'No, I'm not going to swing. Yadi (Molina) was like, 'Swing.' I was like, 'All right!' So I swung, and it was pretty cool. It felt like spring training or something. It felt like a drill."

Cardinals manager Mike Matheny was unfazed by the happenings on the field.

"We want the replay to get things right, I get that," Matheny said. "Part of that is getting the baserunning thing right, too."

Lohse added that he didn't watch the runners or Morse as they re-enacted the play.

"I don't really care," he said. "It was weird. I probably would have started laughing if I saw it --what Morse did afterwards, the dry swing. I knew it was a homer, so I was just trying to restart."

Lohse said he knew Morse's drive would be ruled a grand slam.

"It was out," Lohse said. "I saw it. The ball had a nice cut on it from (hitting) the sign. I knew it was out."

Lohse doesn't know when, or whether, he will pitch again this season. The Cardinals' lead over the Los Angeles Dodgers fell to two games with four to play after the Dodgers defeated Colorado 3-0. The Cardinals' magic number remained three.

"I don't know what's next," Lohse said. "They haven't said anything. We've got to get there first, get into the postseason."

Contact reporter David Wilhelm at dwilhelm@bnd.com or 239-2665.