World No. 1 Roger Federer joked that Nick Kyrgios was a player he did not want to face, particularly in a five-set match.

Federer is currently taking part at the Halle Open in Germany as he will be looking to win his fourth title of the year, following his triumph at the Mercedes Cup last week where he defeated Milos Raonic in the final.

His win in the semifinal over Kyrgios however, saw him once again become the No. 1 ranked player in tennis as he took a 150-point lead over Rafael Nadal in the ATP rankings.

It was not without Federer digging deep however, as he was once again taken to tie-breaks by the mercurial Australian before eventually winning the match 6-7, 6-2, 7-6.

It took his head-to-head record against Kyrgios to two wins in their three meetings in what is quickly becoming one of the most fascinating match-ups in recent history. Kyrgios is regarded as arguably the most talented youngster on the ATP Tour today and notably thrives playing against the top-ranked players.

The 23-year-old defeated Federer at the Madrid Open in 2015 while he also holds a combined five wins in 13 matches against the likes of Nadal, Novak Djokovic, and Andy Murray — the most recent of which came against Murray at the Queen's Club Championships on Tuesday, albeit the Briton was playing competitively for the first time in 11 months.

Just the second player to defeat Federer, Nadal and Djokovic in his first meetings with them, Kyrgios however, suffers from a lack of motivation sometimes, evidenced by occasional losses to players outside the top 100.

But with the world No. 21 currently in good form ahead of Wimbledon next month, Federer does not fancy playing him at SW19, especially as eight of the nine sets they've played against each other have all gone to tie-breaks.

"I’d rather not play five-set matches against Nick because they would last too long and we would probably both grow beards before the end," Federer was quoted as saying by the Express. "I’m a fan, really. He plays very relaxedly, just like me when I was young."

"Fortunately, I changed then, so I could become really successful. But it’s good to have guys like him on the tour. With him it's more about being focused to motivate himself again, doing the same on every point."

Meanwhile, Kyrgios was disappointed to lose to the Swiss legend but only had praise for his ability, especially on his preferred grass surface.

"He [Federer] just looks efficient," Kyrgios said before his win over Murray. "He looks so comfortable on the grass. I have never played anyone with a better sort of serve and first ball, especially on the grass. He just takes all the time away and he seems so relaxed. His block return on his backhand side is money."

"Yeah, he just looks relaxed. He looks in form. The last couple of months wasn't from injury for him. He's just been chilling out and getting ready for this grass season. He's very dangerous at the moment," Kyrgios added.

Federer plays Benoit Paire in the round of 16 of the Halle Open on Thursday next while Kyrgios plays in the round 16 the same day as well against Kyle Edmund at the Queen's Club Championships.