James Blake has warned Andy Murray it would be dangerous to play at Wimbledon if he is anything less than 100% fit.
Blake is seeded nine for Wimbledon
"If you're 90% then you shouldn't play because the difference between being top 10 like Andy is and top 80 or 100 is maybe 5%," said the American.
"I know from experience when I have played a bit injured, it's dangerous.
"You say you'll be careful but you're not. You are so competitive, you want to win so badly and when the adrenaline starts, you don't know when to stop."
Murray, who has been seeded eighth for Wimbledon, is set to make a late decision on whether to take part as he recovers from tendon damage in his right hand.
But Blake, a place lower than the Scot in the world rankings at nine, doubts Murray would progress very far at SW19 if he is still carrying the injury.
"If you're playing at 90% you won't win very many matches. And you are possibly going to injure yourself worse, because you haven't felt the pain when there is so much adrenaline.
"Then after the match you realise you have hurt it worse and it becomes a chronic thing.
"If Andy is still injured and the doctors don't think he is all right, then I would listen to the doctors.
"But if there's no way he can re-injure himself again then he has earned the right to be in the draw and be one of the top players."
The first thing you look at as a male player is if you are in Federer's half of the draw
Roger Federer and Rafael Nadal are seeded to meet each other in the Wimbledon final for the second year in a row.
But Blake, 27, believes compatriot Andy Roddick, a two-time Wimbledon finalist and a winner at Queen's for a fourth time last week, remains the biggest threat to Federer's chances of winning a fifth straight title.
"In my opinion Andy is still the second best grass-court player in the world. I would put Andy second favourite after Federer."
"The first thing you look at as a male player is if you are in Federer's half of the draw," he added.
"My record against Nadal is pretty good (3-0), although all those wins have been on hard courts - on clay the record might be reversed!
"We've never played on grass so that could be interesting but it's tough to compete when you're up against possibly the best player ever (Federer) and possibly the best clay-courter ever (Nadal).
"But you just have to do your best and take advantage when they do falter, because everyone has a bad day once in a while."
Blake will join Murray and Henman at the UK leg of Turbo Tennis on 15 September at the 02 Arena in London.