Popular Twitter account @Tennis TV tweeted footage from the O2 of Federer conducting an interview with Sky Sports on Friday morning.
But the interview was gatecrashed by his ATP rivals David Goffin, Grigor Dimitrov, Marin Cilic and Alexander Zverev, who sneak up on him in the background and take him by surprise.
@TennisTV tagged Federer in the tweet and wrote: “Sneak attack on Roger… #NittoATPFinals @rogerfederer.”
Rafael Nadal can be seen nearby conducting his own interview with another member of the media.
Federer says in the footage: “And here they are, look at them. Now you see I have to be careful what I say!”
The 19-time Grand Slam champion noticed the tweet and responded by writing: “I’ll have my revenge!”
Nadal is facing a race against time to be fit for his opening clash on Monday – although he insists he will take to the court to face David Goffin.
He said: “I’m going to play – that’s what my feeling is today. I can’t predict what might happen in the next couple of days, but my feeling is that I’m here to play and to try my best.”
On whether his great rival will take part, Federer added: “He’s the No 1 player in the world, had the best season of us all and is a superstar of our game.
“So naturally it would be a blow. If he’s here, to me that’s a good sign.”