The New York Red Bulls spoiled Atlanta United's Major League Soccer bow as a Daniel Royer header and Anton Walkes own goal lifted them to a 2-1 win over the expansion club on Sunday.
Atlanta were off to a dream start in front of home fans in their first ever match, leading 1-0 thanks to Yamil Asad's 25th-minute opener.
But a mistake from Alec Kann gave the Red Bulls a corner and Royer rose to head home Sacha Kljestan's effort in the 76th minute.
Six minutes later, Kemar Lawrence played a ball toward Bradley Wright-Phillips that deflected in to stun the 55,297 in attendance for Atlanta's MLS debut.
The goal was eventually ruled an own-goal by on-loan Tottenham prospect Anton Walkes, who had come on for injured defender Leandro Gonzalez Pirez.
Atlanta's frustration was evident when midfielder Carlos Carmona was shown the first red card in the 88th minute.
Atlanta will try to bounce back next weekend at Minnesota in a clash of first-year expansion clubs.
In Orlando, Cyle Larin's header in the 15th minute was enough to let Orlando City SC open their new stadium with a 1-0 victory over New York City FC.
It wasn't all good news for Orlando, however, as Larin's header came minutes after Brazilian veteran Kaka limped off with a left hamstring injury that coach Jason Kreis described as "potentially serious".
He was replaced by Giles Barnes, who took advantage of his opportunity with a deft cross to set up Larin's goal.
"I saw Giles get the ball and he looked up once, and, as soon as he did, I knew he was going to cross it back post," Larin said. "Obviously I wanted a goal, but I wanted the win more and that was the most important thing – winning the game for the fans and this organization."
After giving up the early goal, a New York team featuring new additions Maxi Moralez of Argentina, forward Rodney Wallace and goalkeeper Sean Johnson controlled the run of play but saw chance after chance go begging.
New York's European imports David Villa and Andrea Pirlo created several scoring opportunities but were thwarted by Orlando goalkeeper Joe Bendik, who finished with seven saves.
Sean Okoli nearly grabbed an equalizer in the 86th minute, but his shot from 25 yards was pushed wide by Bendik as Orlando withstood a last press from New York.
Orlando and New York City both entered the league as expansion clubs in 2015 and played their inaugural game against one another.
Orlando played their first two seasons in the ageing Citrus Bowl stadium built for American football before unveiling their new 25,500 capacity state-of-the-art home.
In a first for MLS the venue features a specially designed "safe standing" terrace for fans who prefer to be on their feet and an area where smoke cannisters can be set off.