Roger Federer’s long-time coach Severin Luthi says the 20-time Grand Slam champion is still "lagging behind" with his fitness as he looks to return to his peak level.
Federer made his comeback in Doha after a year out in February, but only played two matches and has not made a competitive appearance since.
He confirmed recently that he is planning to play at the Geneva Open in mid-May before Roland-Garros and then turning his attention to his main targets on grass.
Laver Cup
'It's a team huddle!' - Team Europe take coaching to next level with Zverev
4 HOURS AGO
But Luthi, who has worked with Federer for almost 14 years, says the 39-year-old still needs time to get back to his best condition.
"In terms of fitness, Roger is still lagging behind, which is a priority," he told SRF.
"Tennis practice sessions are very intense and good, but are not taking place that often yet like they would be in a tournament environment."
Reflecting on his relationship with Federer, Luthi added: "Roger is a very good listener, that's important. But I see us coaches more as consultants. In the end, he decides on the court.
"I just try to do everything in my power to help him. I try to exude a certain calm. If I have the feeling that it is appropriate to show emotions or to get up, then I'll do it.
"Roger gives you a lot back. I've learned a lot on the human side."
Federer beat Dan Evans in his first match back in Doha before losing to Nikoloz Basilashvili in three sets.
He has said that his season will start properly on the grass as he looks set to play Halle before targeting a 21st Grand Slam at Wimbledon.
Ivan Ljubicic, who also coaches Federer, says that the aim is still to win "big titles".
"Roger Federer is doing very well, he is set to be back in Geneva," he told Gazzetta dello Sport.
"In Doha he showed he is still able to achieve something, so we are confident. Hopefully he can play many matches to find rhythm again. We want to win big titles."
Laver Cup
'I don't think his hands are that good' - Zverev coaches Ruud mid-match
YESTERDAY AT 20:06
Laver Cup
'It's special, awesome to see' - Laver and Federer get standing ovations at Laver Cup
YESTERDAY AT 18:22