Brad Gilbert believes the last few months will have been “mentally taxing” for Novak Djokovic and is unsure whether he will dominate the clay season.
Djokovic, 34, has played just three matches this year after being denied entry into Australia and the United States as he is unvaccinated against Covid-19.
The only event he has played was in Dubai, where he won two matches before losing to qualifier Jiri Vesely.
He will return to action at the Monte-Carlo Masters next month and is expected to play several clay events before the French Open.
However, Gilbert, who coached Andre Agassi, Andy Roddick and Andy Murray, is not sure how he will fare due to the lack of match practice.
“Before any of this with Covid happened, I thought that Djokovic would be unstoppable around this time. [But now], it’s all just a mystery with him,” Gilbert told Patrick McEnroe on the Holding Court Podcast.
“I just think that when you get so much equity by winning matches – which he had tons of – and all of a sudden you’re not playing and all this thing that happened with Covid, I think it’s been mentally taxing.
“Now, it’s kind of forgotten, but the guy has been there the whole time is all of a sudden gone. I think even if he gets to play all through Europe, I gotta see results and I gotta see how he gets his game back. Maybe he will get it back.”
Seven-time Grand Slam champion Mats Wilander thinks Rafael Nadal’s rib injury means Djokovic is now the favourite to defend his French Open title.
However, Gilbert sees another potential contender.
Carlos Alcaraz, 18, has been one of the most impressive performers this season and Gilbert thinks he could upset Djokovic on a big stage.
“I want to see see Carlos Alcaraz play him. I think Alcaraz is going to come on court and play him and think, ‘OK, he’s not the same.
“I think if someone is going to play him in the fourth round of a Slam, if you like to bet, put a few on Alcaraz.
“He’s right there and I like his chances of winning one of the next four Slams. I like what Rafa said about him: he’s humble. When you are humble you work hard. He kept referring to how humble he is and how hard he works.
“He’s got a live arm and a very strong serve. I think he has a very good chance to win a Slam as a teenager.
“I would actually put the odds in his favour that he wins a Slam as a teenager as opposed to as not.”
