THIS IS AWESOME!!!
Some of the greatest tennis players EVER -- from Serena Williams to Roger Federer -- hit the court Wednesday ... and it was all to help raise nearly $5 MILLION for Australia fire relief!
With The Australian Open set to kick off next week ... legends like Rafael Nadal and Novak Djokovic joined Serana and Federer at Rod Laver Arena in Melbourne to get some pickup games in for charity.
The event was great ... the superstars hammed it up for the crowd, got in a little tennis action and, most importantly, raised roughly $4.