With the score tied at 2, Tatis led off the sixth inning and drove an 0-1 pitch from Josh Johnson to left field. A fan reached over the railing above the high fence in an attempt to catch the ball, which ricocheted back onto the field.
Second-base umpire Dale Scott signaled home run almost immediately, but Marlins manager Fredi Gonzalez came out to argue for fan interference. The umps huddled on the infield and then three of them disappeared under the third-base stands.
After a few minutes, they returned to the field and upheld the call. It was the first replay review at the Mets' new ballpark, Citi Field.
"All four of us had home run, but what with the technology we have today, you might as well take a look," said Scott, the crew chief. "We looked at three angles. Two were not very good. One was a great angle that clearly showed the ball hitting above the line."
Replays showed Tatis' drive clanged off the bottom of the railing that sits above the orange line atop the left-field fence, which is nearly 16 feet high.
"I thought that it was below the line. I can't ask for a replay, but I guess it was close enough for them to go check," Gonzalez said. "I know that it was touched by the fan, but I thought it was below the orange line. I can ask for them to get together on the field, the four guys. And that's what they did."
As players waited for the call, New York starter Johan Santana stood in the dugout twirling his finger in the air to signal home run.
Johnson didn't appreciate the delay.
"I wasn't very happy. Let's go -- so I can try to get out of this inning," he said after the Marlins rallied for a 4-3 victory.
It was the fifth time replay has been used to review a homer this season. All five calls have been upheld -- including two at the new Yankee Stadium across town.