Pat Cash believes tennis 'bad boy' Nick Kyrgios can reach a grand slam semi or final but probably won't go to the top of the rankings.

The former Australian tennis star believes the emotional nature of the 22-year-old, who is currently number 18 in the world, will stop him from cracking the top three in the future.

But Cash still believes his compatriot can land a grand slam title during his career as Kygios prepares to take on the likes of Roger Federer and Rafael Nadal at the US Open next week.

"I have always said Nick will be a danger at the slams but unlikely to get to top one, two or three, as he is an emotional player and that is draining and leads to inconsistent performances,'' Cash told ESPN.

"But he still has the potential to get to a slam semi or final - as long as he is fresh and fit.''

Following the withdrawals of so many male stars, Kyrgios is being tipped by some to go very deep in the draw at Flushing Meadows.

Milos Raonic is the latest name to pull out, joining Andy Murray, Novak Djokovic and Kei Nishikori on the sidelines.

Kyrgios has previously reached the quarter-finals at Wimbledon in 2014 and the Australian Open in 2015, but he has never made it past the third round of the US Open.

But, after a runner-up finish at the Western & Southern Open in Cincinnati, Kyrgios will be looking to make his mark on the upcoming tournament.