Roger Federer's coach Severin Luthi has admitted that the 20-time Grand Slam winner is fighting a losing battle to be fit for this year's Wimbledon.
Federer went under the knife to address a knee issue for the third time after his Wimbledon exit to Hubert Hurkacz last year and has not taken to the court since the surgery in August.
The 40-year-old unsurprisingly missed the Australian Open ahead of a possible return to the All England Club in the summer, but Luthi has poured doubt over his chances of competing at the tournament.
Speaking to Swiss newspaper Tages Anzeiger, Luthi said: "At the moment, I don't envisage him playing Wimbledon. I'm not someone who is saying it's impossible. But I can't imagine it right now.
"This week, to warm up, he will first hit some balls with Mirka (his wife). He can always do more, he is actively working. He's still in the rehabilitation phase.
"Not only do the knee and leg muscles have to be built up, the whole body has to be strengthened. It's a full conditioning program. The main thing for him is to slowly get back in [to the top ten]."
Federer's most recent of his eight Wimbledon triumphs came in the 2017 edition, and the Swiss has not claimed an ATP title since winning the Swiss Indoors in October 2019.