Novak Djokovic says he will only play at this year's Wimbledon if he can "fight for the title", but his recovery from knee surgery is going "in the right direction".
The seven-time champion tore the medial meniscus in his right knee at the French Open and had surgery less than three weeks ago.
He intends to decide on whether he will play at this year's Championships, which start on 1 July, before the draw is made on Friday.
He trained for nearly two hours at Wimbledon on Monday, with a support bandage on his knee, and said afterwards that it was "great" to be back at the All England Club.
"I didn’t come here to play a few rounds," the 37-year-old told BBC Sport after his session.
"If I know I can play close to my maximum or at maximum, then I'll play. If not, then I'll give somebody else a chance to play."
Adding he "liked his trajectory so far", Djokovic said: "I really will only play if I know I am in a state which is good enough to go far in the tournament and fight for the title, so that's the condition."
Cameras were trained on Djokovic as he practised his groundstrokes, serving and volleying on the Aorangi practice courts.
He was hitting with Argentina's Federico Coria, and the pair played two tie-breaks, the first of which Djokovic won and the second he lost.
"Rehab is going in the right direction every single day, a few per cent better and better. That's what's giving me hope and encouragement to keep going," he said.
"I'm taking things gradually. I'm not pushing myself yet 100% but I'm hoping that's going to come in the next few days."
Should he play at Wimbledon this year, Djokovic would be making his 19th appearance at the grass-court Grand Slam.
He has reached the Wimbledon final for the past five years, losing the 2023 showpiece to Carlos Alcaraz in a memorable five-set match on Centre Court.
Later this summer, Djokovic will represent Serbia at the Paris Olympics as he targets the gold medal that has so far eluded him.
Paris will mark his fifth Olympics but he has only won a bronze medal, at his first Games in Beijing in 2008.
BBC