Pat Rafter has joined fellow Australian tennis icon Rod Laver in calling for Nick Kyrgios to be suspended for his latest series of outbursts during the US hardcourt season.

Kyrgios has already been fined for $167,000 for his meltdown at the Cincinnati Masters last month, where he appeared to call umpire Fergus Murphy a "f---ing tool" and smashed two racquets during a bathroom break Murphy tried to stop him from taking.

Nick Kyrgios is a huge hit with tennis audiences. Credit:Getty Images

Asked about the fine after his first round victory at the US Open, Kyrgios said: "The ATP is pretty corrupt anyway."

He took to Twitter to clarify the comments a day later but remains the subject of an ATP investigation.