Serena Williams -- DISCO DANCE BATTLE ... With Novak Djokovic

They destroyed their competition on the court -- but there was one last match for Serena Williams and Novak Djokovic last night ... an all out disco dance battle!

It all went down at the Wimbledon champion's dinner in London --where the two were onstage being honored by a bunch of fancy Brits ... when the band began to play "Night Fever" by the Bee Gees.

There was some awkward disco pointing by Novak ... a valiant effort ... but in the end, IT WAS ALL SERENA!

Afterward, Williams tweeted ... "Wimbledon champions/ Clowns 😜 congrats @djokernole we brought back the dance!"