Individually, they've dominated the tennis rankings and battled for top spot for the better part of a decade.
And now it looks as though they're ready to tackle the music charts.
General G.O.A.T. Roger Federer posted the video below to Twitter, which shows the group of Grigor Dimitrov and Tommy Haas belting out a tune with David Foster on the piano. Check out the clip below.
The group have tackled Hard To Say I'm Sorry by Chicago, and while it sounds like there may be a bit of auto tuning, we'll allow it (purely because of the choreographed dance moves).