Roger Federer admitted that he is suitably impressed with Nick Kyrgios' form over the past month.
The Australian has knocked out world number two Novak Djokovic in consecutive tournaments, meaning he now has wins over each of the Big Four in men’s tennis: Andy Murray, Rafael Nadal and Federer.
The Swiss Maestro has only faced tennis' bad boy once – in a thriller where each set went to a tiebreaker – at the Madrid Masters in 2015, where Kyrgios came back from a set down to win.
Now, they meet in a tantalising semi-final at the BNP Paribas Open at Indian Wells on Friday.
"I'm very impressed him taking out Novak, back-to-back weeks, on Novak's best surface," Sky Sports quotes the 35-year-old as saying.
"It goes a long way for all the players – not that he needed to prove his point – but I think now he has really arrived on the scene.
"He's beaten all the guys: Novak, myself, Rafa. It's very impressive."
Meanwhile, Kyrgios is 7-3 for the year and is eager to bounce back from a frustrating 2016, where his emotions often got the better of him, leading to a suspension and a number of fines.
"I was in a pretty dark place," said the world number 16.
"Even I was at 13th last year, but I wasn't in a good place mentally at all. I was beating myself down, and I just wasn't in a good place.
"[Now] I'm just trying to stay happy and just try and enjoy my tennis a little bit."