Isner decides against playing Rio Games

American world No.18 John Isner has joined Austrian Dominic Thiem in deciding to skip the tennis event at the Rio Olympic Games

American world No.18 John Isner has decided to skip the tennis event at the Rio Olympic Games (AAP)

American John Isner will not be available for the Rio Olympics, with the US No.1 joining Austrian Dominic Thiem in giving the August Games a miss.

"It's a decision I didn't take lightly," Isner, ranked 18th, said.

Isner lost to silver medallist Roger Federer in the quarter-finals of the 2012 London Olympics.

He seems to have his heart set on playing the minor ATP Atlanta stop, which will be held the week before the Games and where he will be going for a record fourth title.

"Logistically, it would be pretty much impossible for me to do both," Isner told US media.

It is also reported that as the Games do not offer ranking points - London did - that Isner is not particularly interested in the competition.