Former world number one concerned about Novak Djokovic's recurring injuries

This was the second time Djokovic was forced to withdraw from a Grand Slam tournament in his last four, as his push to win another French Open title was also cut short by injury last year.

With this latest injury expected to rule Djokovic out of action for two months, Roddick expressed concern that the Serbian's body may continually let him down as he reaches the back end of his tennis journey.

Djokovic beat Tomas Machac and Carlos Alcaraz in impressive fashion before limping out of his semi-final against Alexander Zverev, with Roddick warning it will get tougher for the Serbian to continue to maintain his immaculate fitness levels as he approaches his 38th birthday.

"Novak was playing great in Australia," he said on his Served podcast, as he asked a question to fellow former Grand Slam champion Kim Clijsters.

"Obviously the match against Alcaraz was great and beating Machac in straight sets was great. Against Alcaraz, set three and four was vintage Novak from two years ago or before.

"He has fought off time as well as anyone in tennis history, but French Open last year it was his knee and he managed it and got to the final of Wimbledon on one leg.

"Now coming into this year, there is another tear and I'd be surprised if we see him for a couple of months.

"I fear that at that age, you get into that cycle of rehab⦠can your body recover? We act surprised every time someone gets older, but it's tough as you have to build up again after an injury."

Roddick also revisited the debate around Djokovic's contentious exit from the Australian Open, as he admitted he felt 'icky' when the 10-time Australian Open champion was booed off court.

Amid bizarre claims that Djokovic was exaggerating his injury, the Melbourne crowd appeared to be annoyed that he was unable to continue the match against Zverev and his exit was an unpleasant end to what may have been his final Australian Open.

"I didn't like it. Listen, you can disagree with someone, it's just booing someone when they're going off, even if you don't know if they're really hurt, you don't boo," added Roddick.

"If you suspect they're not hurt, there's a chance that they're telling the truth, you don't boo.

"I just hated the fact that he's leaving the court to boos and I understand he likes the friction, he invites the friction in, he thrives off of it and at times has created controversy because he operates well in that space.

"I get all that but at a certain point if you're a tennis fan respect has to win out.

"I'm not telling you to cheer for someone that you don't want to cheer for, I'm saying there's a million miles between not being an out-and-out fan of someone and also booing someone who's one of the all-time greats.

"You don't know if you're going to see them again. I didn't like that, it made me feel icky on the inside. I didn't like that."

Djokovic posted an MRI scan of his injury in an attempt to banish the notion that he was not as injured as he suggested, with the whole episode leaving an unpleasant taste that showed disrespect towards a true great of the game.

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