The former coach of Nick Kyrgios has ranked his Miami Open semi-final showdown against Roger Federer as the greatest non-grand slam match ever played.
Australian coach Todd Larkham described the three-set thriller as the best game of tennis he's ever seen, outside of the majors.
The Canberran fell two points short of the most significant scalp of his budding career as the Swiss maestro prevailed 7-6 (11-9), 6-7 (11-9), 7-6 (7-5).
Larkham, who coached Kyrgios for almost a decade before the pair amicably split in 2014, said the match was played at an "incredibly high level" from start to finish.
"The match with Nick and Federer was possibly one of the greatest matches outside a grand slam that I've ever seen," Larkham said.
"There was nothing in it, only a couple points, and Nick has shown he can match it with anyone now which is awesome.
"They both played an incredibly high level of tennis, Nick is a great competitor but so is Federer and it came down to just a few points in the tiebreak where Fed came up with the shots."
Larkham said Federer's return to tennis after a six-month injury layoff has been nothing short of remarkable with the world No.4 dropping just one match this year.
"He's playing amazing tennis, he finds a way to continue to win these close matches and he's won a lot of close ones this year," Larkham said.
"Physically he's still got a couple more years in him which is incredible, he just plays so efficiently and fluently and doesn't seem to expend the energy of his opponents.
"We love watching great champions in all sports and it's awesome to see him keep going and building on his record which is already the best ever."
Australia face the US in a highly-anticipated quarter-final Davis Cup clash in Brisbane this week, with Lleyton Hewitt leaving controversial world No.43 Bernard Tomic out of the team.
The Aussie skipper named an unchanged quartet in world No.16 Kyrgios, emerging talent Jordan Thompson, big-serving Sam Groth and John Peers to play doubles.
The American team is expected to feature world No.15 Jack Sock, John Isner, Sam Querry and Steve Johnson.
Larkham believes Kyrgios' form and his addition to the team which lost against the US at Kooyong last year, will prove the difference.
"Nick is in better form and he didn't play last time so I think we've definitely got a better chance," Larkham said.
"It was pretty close in Melbourne, Isner played well on the grass and his serve was unbreakable, but I think on the hard court it will be easier to break him, so we're definitely in a better spot there.
"Based on form Nick would be the slight favourite to win his singles matches, he's been playing better than the other guys, but Jack Sock has been playing well this year.
"Jordan is definitely the underdog in his singles matches. That probably balances things out then the doubles is a 50-50 but John Peers is a top-five doubles player and him and Grothy have been playing well."
Australian coach Darren Cahill told Fairfax Media that Kyrgios doesn't necessarily need a mentor to succeed, and although Larkham chose not to comment, he said there is no denying the coachless Kyrgios is playing world-class tennis.
"He's in great form and it's great to have him playing Davis Cup tennis for Australia in Australia," Larkham said.