The one thing Roger Federer can't do well?

Roger Federer poses for a photograph in front of the Miami skyline after defeating Rafael Nadal on Monday. Photo / AP

He's one of the greatest tennis players of all time who is back at the top of his powers at age 35, but Roger Federer has shown he does lack one skill - passable acting talent.

The world number four posted a promo for a charity event with Bill Gates on Twitter today.

In the promo, Gates plays a fan in an empty stadium who continues to shout out support for the Swiss star.

Federer's home country is known for its cheese and the tennis player's performance doesn't lack any with a very cheesy delivery with his final line.

It's fair to say rival Rafael Nadal is a better actor after convincing fans that he wasn't Rafael Nadal in a stunt for sponsor Poker Stars in 2012.

Both have improved considerably since their effort in 2010 to promote a charity event.

The 18-time Grand Slam champion and the billionaire Microsoft co-founder will pair up in a one-set exhibition match in Seattle on April 29 to support children's education in Africa.

Federer and Gates will play against John Isner - the American who won the longest match in tennis history - and an as-yet-unannounced celebrity partner.

Then Federer and Isner will square off in a best-of-three-sets singles exhibition.

Proceeds from the Match for Africa 4 will benefit the Roger Federer Charitable Fund and Roger Federer Foundation.

Federer added to his record total of major championships by winning the Australian Open in January.

He is 19-1 this season, including a title at Key Biscayne, Florida, on Monday.