The score was tied at 3 when controversy clouded the inning and helped the Mets score the go-ahead run. With runners on first and second and one out, it looked like Fernando Tatis swung and missed on a 3-2 pitch, but home-plate umpire Rob Drake ruled that Tatis didn't swing and was awarded first base.
"That's the human element part of the game," manager Manny Acta said. "The video showed that Tatis swung the bat. He struck out."
Then, with the bases loaded, Rivera's 1-2 pitch appeared to sail over the head of Damion Easley. Drake, however, ruled that Easley was hit in the helmet and it allowed David Wright to score the go-ahead run.
Catcher Jesus Flores disagreed with the call, claiming that the ball hit Easley's bat. Acta then came out of the dugout and argued for several minutes, but the call stood.
After the game, Acta looked at the replay and agreed that Drake made the right call.
"I thought the ball hit the bat, but the umpires got it right -- the ball hit him in the helmet," Acta said.
Drake was nit available for comment.
Rivera giving up the go-ahead run didn't bother Acta as much as his team's lack of execution on offense.
Take the fourth inning. The Nationals had runners on first and second and no outs, but Willie Harris hit into a double play and left-hander Odalis Perez grounded out to end the inning.
But the big disappointment came in the sixth inning. With Lastings Milledge on second base and no outs, Flores came to the plate and bunted the ball right to pitcher Johan Santana, who easily threw out Flores and Milledge stayed at second base.
Acta acknowledged that Flores made a mistake. The team was looking for Flores to swing away because he is the team's leading RBI producer. Bunting was the last thing he should have done.
"The reason we didn't win the game was because of our poor execution at the plate," Acta said. "That's part of the growing pains that you go through when you are dealing with 23 year olds. That's a play Flores did on his own. The guy is leading our club in RBIs. He is already 2-for-2 and he is hitting [over .340] against lefties. I don't think he should be bunting in that situation."
Flores admitted that he made a mistake. He said all he was trying to do was advance the runner.
"I was playing for the team. I was trying to move the runner," Flores said. "The decision came from me. [Acta] told me I'm the guy and I had the opportunity to swing -- don't miss the opportunity to swing the bat."
Perez started for Washington and he pitched six solid innings, giving up three runs on eight hits. Most importantly, he gave most of the relievers a rest.
Perez got off to a slow start as the Mets scored two runs in the first inning. Carlos Delgado hit a two-run single to drive in Nick Evans and Carlos Beltran.
But the Nats answered back against Santana in the bottom of the inning. With one out, Ryan Zimmerman singled to right-center field to drive in Cristian Guzman. Three batters later, Flores singled up the middle to score Zimmerman.
"Pretty much after the third inning, everything was working. My fastball was good," Perez said.
The Mets then took a 3-2 lead two innings later as Beltran doubled home Wright.
But, in the seventh inning, the Nationals tied it again, thanks to a pinch-hit homer by Ryan Langerhans.
The Nationals couldn't do any more damage after that, as relievers Joe Smith and Pedro Feliciano shut out Washington the rest of the way.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.