The Leeds stars were delighted for the rugby side.
Indeed, the Rhinos beat Wigan Warriors in a dramatic final at Old Trafford, leaving Manchester with a 22-20 win to secure a famous treble.
And Leeds' football team were quick to send their congratulations on Twitter.
Cooper is very much in favour among Leeds supporters right now, with Giuseppe Bellusci out of form, while Phillips has struggled for game time in midfield recently - although he started the season well.
RHINOS!!!!!— Liam Cooper (@LiamCooper__) October 10, 2015
Leeds United aren't close to replicating any treble attempts themselves just yet but a crucial period that can boost their season does await them after the international break.
Having had several days to work with his players at Thorp Arch, Uwe Rosler will be looking to get the Yorkshire side firing once again.
They face a tough immediate task, of course, against Championship leaders Brighton. But perhaps they can take their inspiration from the Leeds Rhinos.
Meanwhile, the controversial Joey Barton also gave his take on the game...