Greg Rusedski has issued a warning to Novak Djokovic's rivals, saying the Serb "looks like a serious threat to win multiple majors" after he reached the final of the Shanghai Masters on Saturday.
Djokovic crushed Alexander Zverev 6-2 6-1 in a near-flawless semi-final display to reach the final in China for the fourth time in his career.
The 31-year old will be targeting his 72nd career title on Sunday, having won all three of his previous finals in Shanghai.
Djokovic has been in imperious form, winning Wimbledon, the Cincinnati Masters and US Open in recent months, after having elbow surgery in February. He is on a 17-match winning streak and is 26-1 in matches played since the start of Wimbledon.
Djokovic told Sky Sports that he had a strategy in place after teaming back up with coach Marian Vadja and his fitness coach Gebhard Gritsch in April, but is "surprised" to be playing some of his best tennis ever this early.
Rusedski said: "I'm not really surprised by it. I thought he would be ready by the French Open, start playing well again.
"As he said, getting his team back together again, Marian Vadja and his physical trainer, you can see that work. Why do something different when the formula hasn't broken? That's what he went away from as well as that injury to his elbow, but getting that team back he's just too good of a player right now.
"He looks like a serious threat to win multiple majors. Right now he's tied with Pete Sampras with 14 Grand Slams, but he looks like the heavy favourite to win the Australian Open. I wouldn't be surprised if he wins all four and holds all four again because he is just getting better match in, match out.
"He has this calmness and aura that was once there when he held all four Grand Slams. The more comfortable that you become in yourself, the easier it is to play."
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