Roger Federer says his failure to deal with the serve of Nick Kyrgios was the reason behind his surprise exit from the Madrid Masters.
The Swiss top seed crashed out 6-7 7-6 7-6 against the young Australian, despite earlier saving five match points.
Kyrgios won the final tie-break 14-12 to claim only the second top 10 scalp of his career after beating Rafael Nadal at Wimbledon last year.
Federer could not hide his disappointment after the match, claiming the Australian’s first serve was just too good on the day.
“I couldn’t return his first serve, I had a horrible performance on return of serve. That made life difficult for me.
“I’m disappointed with how I played on returns, and that cost me the match.”
The match lasted a gruelling two hours 37 minutes and Kyrgios will now meet the big-serving American John Isner in the next round.
“I think he’s the greatest of all time. I knew before the match that I would have to play one of the greatest matches I have ever played, I wasn’t intimidated at all,” Kyrgios said.
“I have a lot of respect for him. It was just another tennis match, it was a chance to go out there and enjoy yourself and I happened to get the win.”
Meanwhile second seed Andy Murray had no such problems when making light work of Philipp Kohlschreiber 6-4 3-6 6-0.
Murray will now face Marcel Granollers in the next round on Thursday.