London - Ivan Lendl and John McEnroe will renew one of the most bitter rivalries in tennis on Sunday as the two coaches watch Andy Murray and Milos Raonic slug it out for the Queen's Club title.
Lendl, in his second spell coaching Murray, and McEnroe, recently hired as Raonic's coach, engaged in a feud lasting over a decade when they were players and now they are back in opposition 24 years after they last glared at each other across the net.
They met 36 times from 1980 to 1992, with Lendl winning 21 of their encounters including a famous fightback from two sets down in the 1984 French Open final.
Those gruelling battles forged a lasting enmity, to such an extent that in his autobiography, McEnroe said Lendl was "a very strange guy, to put it charitably - with an odd, harsh demeanour - kind of bullying and babyish at the same time".
The old enemies are on much better terms these days but, given the contrast between the icy Lendl and the emotional McEnroe, there will be plenty of eyes trained on the courtside coaching box at the Wimbledon warm-up event on Sunday.
Lendl, an eight-time Grand Slam winner, has returned to working with Murray two years after the United States-based Czech called time on a successful spell that saw the Scot win two Grand Slam titles and an Olympic gold medal.
Intrigued by the 56-year-old's success with Murray, and Boris Becker's even more fruitful partnership with world number one Novak Djokovic, seven-time Grand Slam champion McEnroe decided he wanted to have a crack at coaching as well and Raonic brought him on board this week.
The colourful 57-year-old appears to have made a positive first impression on world number nine Raonic, who is through to his first Queen's final.
Fittingly, the old foes are back in combat 26 years after Lendl beat McEnroe in the Queen's semi-finals in what proved to be one of the last matches in their great rivalry.
But defending champion Murray, who is bidding to win a record fifth Queen's title that would surpass a group including McEnroe, refused to be caught up in the coaching talk.
"I'm playing Milos tomorrow; I'm not playing John. Ivan is not on my side of the court," Murray said.
"Obviously the coaches are there in the box, and they are doing their best to help us and prepare as best as they can for the matches.
"But the only people that are there on the court are me and Milos. It's up to us how we perform when we're out there.
"They can't serve for us at an important moment and they can't hit a return for us on break point."