Andy Murray has "no chance" of winning another Grand Slam title, according to former Wimbledon champion Goran Ivanisevic.
The former world No 1 recently revealed he contemplated retirement a matter of weeks before winning the European Open in Antwerp last month.
But gaining more confidence during tournaments in Zhuhai, Beijing and Shanghai, the Scot produced a remarkable level of consistency to win in Belgium - his first title since 2017.
Although he was only able to compete in one match for Great Britain at last week's Davis Cup, Murray confirmed he was "ahead of where I expected to be at this stage" with regard to his hip.
Ivanisevic, who is the current coach of Novak Djokovic, was brutally honest in his assessment of three-time Grand Slam champion ever winning a major again.
"A Slam? No chance. But he can make some surprises, he can go far but to win I don't think that he can survive seven matches - best-of-five," said the 2001 Wimbledon champion, who was speaking ahead of the Champions Tennis tournament at the Royal Albert Hall.
"It's only about health - if he's healthy and the hip is okay I don't think that anyone wants to play against Andy next year. He's a great competitor and when he steps on the court, he wants to win. He's not good for the opponents.
"It's going to be good. I don't know what ranking, it's tough to say no, but if he's healthy he can be up there."
"Andy, I think I agree with Goran. He'll do well at the Slams and I think that he'll be competitive, but to win a major that is hard enough when you're healthy," added Rusedski.
"He's the only British man to win an ATP tour event this year as well, that just shows what an amazing competitor he is and his desire to actually come back.
"Most people, wouldn't be accomplishing what he's done. It's up there, from an emotional point of view and a satisfaction point of view, with his major trophies."
Henman, who was chosen by Murray to captain the Great Britain team at the ATP Cup in January, has backed the 32-year-old to prove the doubters wrong once again.
"I don't think 'can't' is the right word, I think that it's incredibly difficult as everyone has alluded to. Fit, healthy, young, and playing the best tennis of your life it's still incredibly difficult," said the former British No 1.
"The challenge with the best-of-five-set matches is massive but we all know that with Andy if you say that he can't do something, he loves to prove people wrong.
"I think it's very unlikely but I would never, with all of these top guys it's very dangerous to write them off. It will be very, very difficult."
Rusedski added: "If he wins a Slam that would be fabulous. As Tim says, if you say he can't, that motivates him more. Also you want him to enjoy his final few years on the tour without putting that immense expectation and pressure on himself, you always do but there's a little bit less of it than it once was.
"Whenever Murray entered a tournament he was expected to win. Why doesn't he win a major? Why doesn't he win this event? Why doesn't he win that? I think that he's in a really nice period of his career if he can stay healthy."
Henman has also backed the current world No 126 to string together some decent results in 2020. He also feels Murray can realistically climb back into the top 20.
"I still look at his movement and believe that it can get a lot better. So, if he can move better then that's a huge part of his game. I think his results can improve," added Henman.
"I think that realistically he can get back into the top 20. I think obviously as you get older and the demands of his game, well have to see how it progresses after that."
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