About 6,000 fans watched Federer practise at the Hopman Cup in Perth on Thursday - three days before the tournament began

Roger Federer can return from six months out and win another Grand Slam, says his former coach Paul Annacone.

The 35-year-old, who has won 17 majors, is due to make his comeback from a knee injury against Britain's Dan Evans in the Hopman Cup in Perth on Monday.

Annacone, who coached the Swiss from 2010 to 2013, told BBC Sport: "Last year was a very tough year for him and he still got to the semis of Wimbledon.

"There is no reason why he can't play at that level again."

Annacone believes Federer's best chance of another major title will come at SW19, where he has triumphed seven times.

The American added: "When you look at his track record, particularly on grass, if he's healthy, it's going to be very difficult not to put him in the sentence as one of the favourites.

"Again, it's about staying healthy, but I absolutely think he can contend for a major title."

Federer has not played since hurting his left knee as he lost in the Wimbledon semi-finals to Milos Raonic in July.

He is competing in the Hopman Cup team event with compatriot Belinda Bencic.

Wimbledon 2016: Roger Federer calls out the trainer against Milos Raonic

'I expect great things because he's a great player'

Federer said he took six months off "so I would be playing for hopefully another two to three years, not just another six months or so".

Having had knee surgery in February 2016, he missed the French Open with a back problem and played only 28 matches in the year.

He last won a tournament in November 2015 - the Swiss Indoors - and has not won a Slam since Wimbledon 2012.

Annacone, who also coached 14-time major winner Pete Sampras and Britain's Tim Henman, believes Federer's extended absence "could be a positive".

He added: "It's given him time to refresh and really get his body healthy.

"Six months isn't critical - it's not what I would call lethal. I know how hard Roger's worked and how professional and meticulous he is about his preparations.

"It is a challenge, but great players love challenges. I expect great things because he's a great player."

Federer can follow Sampras example

Federer, who has spent 302 weeks as world number one, has fallen to 16th in the rankings, his lowest position since May 2001.

That means he could face Britain's world number one Sir Andy Murray or defending champion Novak Djokovic as early as the fourth round of the Australian Open, which starts on 16 January.

Having reached the semi-finals in Melbourne last year, an early exit would further impact on his ranking.

Annacone feels that will not matter to Federer at this stage of his career, citing the example of Sampras, who won the US Open in 2002 as the 17th seed.

"It's not ideal but I'm a glass half-full guy," said the 53-year-old. "I would imagine if you talked to Andy or Novak they're not going to want to be playing Roger in the round of 16 or third round either.

"I was with Pete Sampras when he won his 2002 US Open. He hadn't won an event for 26 months. With these great players, you just don't know what they're capable of. The rules don't apply - they're merely suggestions.

"I remember it with Pete. He said: 'I really don't care what my ranking is, it doesn't matter any more. It's about can I put myself in position to win tournaments, and in particular major tournaments.' I'm sure Roger's approaching it the same way."

As if to underline that, Federer said on Friday: "Winning titles is a beautiful feeling; rankings at the moment... completely secondary. As long as I'm healthy, I think I can really do some damage."

Annacone coached Sampras to nine of his 14 Grand Slam titles

Can he make more history?

Federer, who has won more Grand Slams than any other male player, will be 36 in August, and Annacone says he does not need to chase history for motivation.

"I just think the sheer joy of competing and the challenge of testing himself against the others will be enough for Roger," he said. "He's so at peace with what he's done and where he is that he'll do it organically by himself.

"If he stays healthy and is able to train and compete as often as he's planning to then I would consider that a success.

"If he does that, his average level, for how talented he is, is going to be somewhere in the top 10 anyway. If that's the case, that average level will create opportunities where he is playing at the end of events."

Annacone, who keeps in touch with Federer "via texts and instant messaging", says the Swiss has been "in good spirits".

"A couple of weeks ago he was doing great, he was really happy in his training in Dubai," he said. "His body felt good and he was really excited about 2017."

But Annacone, who will be commentating on the Australian Open for Tennis Channel, says Federer must "stay patient" in the early stages of his comeback.

"He is so meticulous in his preparation that I expect him to play pretty terrific tennis pretty quickly," he added.

"Now can he do it second event in, the Australian Open, for seven matches? That's a big challenge but he's done it so many times in the past."