Lleyton Hewitt is backing Nick Kyrgios as a French Open dark horse capable of causing serious carnage at Roland Garros.

Kyrgios, who celebrates his 22nd birthday on Thursday, launches his 2017 claycourt campaign as top seed at next week’s Millennium Open in Estoril.

Hewitt is tipping a smooth transition from the fast to slow courts when Kyrgios returns from a well-deserved three-week break to the scene of his maiden ATP final appearance in 2015.

A former grand slam quarter-finalist on Wimbledon’s hallowed grass and Melbourne’s hard courts, Kyrgios also boasts Roger Federer’s prized scalp on clay.

And fresh from watching his singles spearhead lead Australia into the Davis Cup semi-finals with straight-set wins over US stars John Isner and Jack Sock, Hewitt is convinced Kyrgios can go deep at the year’s second major, which begins on May 22.

“He can do well, especially with where his ranking’s at at the moment. “He’s going to be a nice seeding going into the French,” the Cup captain told the RSN Breakfast Club.

“You’ve always got to be wary of dangerous floaters at the French Open because there’s so many good claycourters, especially from Europe.

“So in some of those early rounds, he’s got to be wary and pay that respect to those opponents, but he could easily get through to the fourth round and the the draw opens up and all of a sudden you’re deep into the second week.”

Kyrgios’s only three defeats in 19 matches thus far in 2017 have come against the red-hot Federer in three thrilling tiebreakers in Miami, Isner in Acapulco and Andreas Seppi at the Australian Open.

His serve was untouchable during forays to three semi-finals and a quarter-final in his past four events and Hewitt believes Kyrgios’s chief weapon will be key to the world No.16 making a deep run in Paris.

“He’s got so much firepower that if he’s serving well he’s still able to serve through a slow clay court and get a lot of cheap points,” Hewitt said.

“And then he can go out and actually be quite aggressive on his return game and put pressure on his opponents.

“And for a big guy; six foot four, he moves bloody well … I’m very comfortable with him on that surface.”