Former world number one Roger Federer said he has no real expectations for his comeback event at the Qatar Open.

Federer has not played competitively since his semi-final exit at the 2020 Australian Open – the 20-time grand slam champion having undergone knee surgery last year.

The 39-year-old Swiss superstar opted not to travel to Melbourne for this year's Australian Open, but he is set to make his comeback in Doha.

Federer, who holds the record for most Qatar Open titles with three – will start his campaign against either Jeremy Chardy or Daniel Evans at the ATP 250 tournament.

"It's been a long year in some ways, especially rehabbing, being on crutches once and then for a second time, and finally I'm back on a tennis court again, working out, playing sets, playing points," Federer said.

"It's a true pleasure, it's a privilege actually after all this time. I didn't expect it to go as long as it did, we are where we are, I'm so excited to be back on a match court, you know, in a few days here.

"I'm really curious to find out how it's going to go, obviously there's an amazing amount of questions marks surrounding my comeback for me personally.

"I don't know what to expect, I know that expectations from myself are extremely low, and I'm just very happy that I'm playing a tournament again, regardless of the outcome of this event."

On whether he had doubts over returning, Federer added: "You always do have doubts, you know, when you have surgery, there are always days when you feel better and worse. But I think overall I am a very positive person, I have a great team around myself, my family, I am also very distracted, and you know, the idea was to be fully fit again, one day. For life or for tennis.

"So equally important to me, actually life is a little bit more important to me, I wanna go skiing and play basketball, I wanna go playing ice hockey, play tennis in the future, with my children or exhibition matches, you name it, so it's definitely worth it to go through all that pain you know. But the goal was, this is not I'm going to go out, I'm not happy with my knee, we're going to fix it, and then I'm going to come back.

"For me there was no other story to it, and rehab wasn't as hard as maybe people make it seem, even though people around me are very impressed how I go about it, but for me it's only but normal to be really, really professional about it."

Novak Djokovic made history after breaking Roger Federer's record for most weeks as world number one on the ATP Tour.

Djokovic surpassed Federer after beginning his 311th week as the number one player in the men's rankings on Monday.

Serbian star Djokovic reclaimed the top ranking from fellow superstar Rafael Nadal in February 2020 and finished as year-ending number one for the sixth time – tying the mark set by Pete Sampras.

Djokovic, who first topped the men's rankings in July 2011, went on to celebrate a record-extending ninth Australian Open title at Melbourne Park in February.

With Federer turning 40 in August and Nadal a year older, the 33-year-old Djokovic has time on his side in pursuit of more history.

Djokovic has won 18 grand slams, two adrift of Federer – who is set to make his long-awaited ATP comeback in Qatar this week – and Nadal.

"I think it's an ultimate challenge to be honest, of course, winning a slam and being in history, the longest-ever number one," Djokovic said in Melbourne last month.

"You can have a great grand slam, a great tournament, a great couple of months, or even a great season but to do it over and over again, to be actually contender for historic number one, you need to play well and have a consistency from January to November, ever single year.

"I've been fortunate to do that and put myself in a position to make history in that regard. I'm very, very proud of that and privileged to be in that position.

"It's also a relief because it has been definitely my main goal, other than winning slams and now that I'll be managing to achieve it, I'll focus myself more on slams and adapt my calendar and schedule because when you're going for number one, you have to play all year and you have to play all the biggest tournaments.

"You can't allow someone else to earn more points than you. It's like a constant pressure, I think, and expectations that you have to deal with. It's definitely fulfilling to achieve that."

Federer now sits sixth in the rankings, having not played competitively since the 2020 Australian Open.

Nadal remains second, though he is set to be leapfrogged by Australian Open runner-up Daniil Medvedev in the next rankings release on March 15.

Russian Medvedev will be the first player, other than Djokovic, Nadal, Federer and Andy Murray, ranked in the top two since July 2005.

Daniil Medvedev will climb to number two in the ATP rankings later this month, with his small step signalling that big change is afoot in the men's game.

The leading two positions have been occupied by a combination of the 'Big Four' ever since Rafael Nadal climbed above Lleyton Hewitt to take second place on the ladder on July 25, 2005.

Nadal, Federer, Novak Djokovic and Andy Murray have all had spells at number one in the years since then, and no other player has had a look-in on those leading two positions.

Within days, however, that is about to change, as the younger generation of players gains a first foothold in the top two.

The ATP, which runs the men's game, said on Saturday that 25-year-old Medvedev is certain to nudge up one place from his current position of world number three when the rankings, are published on March 15.

The Russian is currently on 9,735 points, 115 points behind Nadal, and he has a first-round bye at the Open 13 Marseille next week.

The ATP, tweeted: "With the release of next week's @atptour draws, @DaniilMedwed is confirmed to become World No. 2 in @FedEx ATP Rankings on 15 March. Medvedev will be the 1st player in the Top 2 since 25 July 2005 other than the Big 4 of @DjokerNole, @RafaelNadal, @rogerfederer and @andy_murray."

Medvedev, who won the ATP World Tour Finals title in November and reached the Australian Open final last month, missed an early chance this week to move ahead of Nadal when he lost in the first round of the Rotterdam Open.

Roger Federer would have the perfect moment to bow out of tennis if he lands a ninth Wimbledon title this year, according to former SW19 hero Michael Stich.

Swiss great Federer has not played on tour for over a year after undergoing knee surgery twice, and Rafael Nadal has matched his tally of grand slam titles during that time.

By winning at the delayed French Open last year, Nadal joined Federer on a record 20 slam titles, with Novak Djokovic just two behind that pair after his Australian Open triumph last week.

At the age of 39, Federer is on the comeback trail and planning to play tournaments in Doha and Dubai in March, building up to Wimbledon and the Tokyo Olympics, key goals for what might prove to be his final season on tour.

"It is clear that at some point he will stop," Stich, the 1991 Wimbledon champion, told Stats Perform News.

"Many would have thought that already five years ago. We have no influence on that. I would wish for him to win Wimbledon and say after the final: 'You know what, I had a sick time, I'll stop.'

"There couldn't be anything better and that would give so much to the sport."

Stich believes it is "questionable" whether Federer will be capable of success on that scale, but he sees Wimbledon as his greatest opportunity.

"You should never write him off because he is a player who has a gifted set of skills that help him to still play tennis that good at his age," Stich said.

"He may have the problem that the younger generation no longer has this huge respect for him because he was out for a year. The mental side plays a big role there.

"But especially at Wimbledon he is certainly still a candidate for the title, because there he has this mental strength, because there he has the greatest joy.

"The nice thing is that everyone is looking forward to his comeback and wants to see what happens. He has nothing to lose. He doesn't have to prove anything to himself, he doesn't have to prove anything to the fans out there. He's really doing it because he thinks he can still win titles."

With Nadal and Djokovic winning the last two majors, the prospect of Dominic Thiem's US Open win last September triggering a sea change in the men's game has fallen away.

According to Stich, the likes of Thiem, Stefanos Tsitsipas and Daniil Medvedev cannot just wait for the old guard to make way and must instead find a way to disrupt their dominance.

"As a spectator and fan, I naturally wish that the passing of the torch would still happen during the active time of the 'Big Three'," Stich said.

"It's the big goal of all young players that they would like to beat a Roger Federer, a Novak Djokovic, and a Rafael Nadal in a grand slam final. An Andy Murray and a Juan Martin del Potro did it. The only two in what felt like 20 years, and Stan Wawrinka, who is not to be forgotten with three titles.

"It's up to the young generation now and they are no longer 19. They are all 22, 23, 26. Dominic Thiem achieved it at the US Open. One would of course wish that they actively shape this transition, but that is looking into the future."

Stich says he has "no idea when that will happen", but he believes there will be another great generation that emerges, just as tennis moved on from the golden era of Jimmy Connors, John McEnroe and Bjorn Borg, and latterly the days when Pete Sampras and Andre Agassi dominated.

"We have a generation in which three players shaped this period extremely," Stich said. "Now is a chance for the others to step into the spotlight. The next generation will follow in their footsteps. I'm not worried about that."

World number one Novak Djokovic is in favour of technology replacing linespeople across the ATP Tour amid the absence of judges at the Australian Open.

This year's Australian Open is being held without line judges as a response to coronavirus restrictions at Melbourne Park, where "Hawk-Eye Live" technology is being used on every court. 

It is the first grand slam to replace all linespeople with technology as the tournament seeks to limit the number of people on court amid the COVID-19 pandemic.

Djokovic was sensationally disqualified in the fourth round of last year's US Open for inadvertently hitting a ball at a line judge during his clash with Pablo Carreno Busta in New York.

Asked about the situation at the Australian Open, defending champion and eight-time winner Djokovic told reporters: "I think back [at the] US Open last year, someone asked me whether I would support the idea of introducing this kind of line call technology at every tournament.

"Obviously providing that the tournament is able to afford financially that kind of investment, because obviously it is an investment.

"I said that I support that, because I feel, yes, I understand that there is a tradition and history and the way we kind of got used to the line umpires being there, and I think it's nice that there is a lot of people and also volunteers with these line umpires that love tennis and love to have an opportunity to be out on the court and be close to the players and be part of a great event.

"But I think when you draw a line that generally I actually am in favour of technology. I think it's proven to be very accurate in this particular instance.  I don't see a reason why we need the line umpires, to be honest, if we have technology like this. I would of course keep the ball kids, but line calls I'm in favour of this technology."

Djokovic was speaking after beginning his quest for a ninth Australian Open title with a 6-3 6-1 6-2 win over Jeremy Chardy on Monday.

The 17-time grand slam champion is trying to close the gap on 20-time major winners Roger Federer - who is absent from this year's event - and Rafael Nadal.

"I respect all of my opponents' records. I think especially Roger and Rafa, what they have achieved over the years. They are legends of our sport, and I admire them a lot," Djokovic said. "They have positively affected my game and my growth, my development and all my success. Wouldn't be what it is if these two guys were not there.

"I have had tremendous rivalries with these two guys and we still keep on going. But I don't want any of their success, if you know what I mean. I'm not jealous of their success or anything like that. I try to build my own authentic career and my own success, and I stick to that."

Djokovic added: "I am always motivated and inspired to achieve big goals and break records. I would lie if I say that's not, you know, something that I'm thinking about or that my attention is not going that way.

"I have been very transparent about the fact that one of the biggest goals is to try to reach the number one of all time weeks' record, and I'm getting closer and closer to that one. That's a kind of a lifetime achievement for me. 

"Grand slams, as well. Of course the Masters events, I think the 1000 events over the years I have managed to be very consistent and win a lot of titles there. Those are the biggest events that we have on the four other than grand slams.  The head-to-head records with top guys as well, to name a few. I try to be a good student of the game. 

"I'm just very fortunate to be in this situation and position that I'm in at the moment, so I try to keep on going and obviously setting up new goals for myself, because I feel like other than passion and love that I have for the game and the biggest reason why I still play it is exactly that pure emotion that I have of enjoyment when I'm there and excitement.

"As a professional tennis player, I need to have goals. Over the last 15 years, everything that I have managed to achieve, I don't settle for anything less but the top of the men's game and the biggest trophies.  That's something I always aim for. I work towards that.  And yeah, I'm still lucky to be where I am. Let's see what the future holds."

Roger Federer is aiming to make his return to the ATP Tour at the Qatar Open, while Rafael Nadal is contending with a back injury with less than a week until the Australian Open.

Swiss maestro Federer has not played since losing in the semi-finals at Melbourne Park to Novak Djokovic in 2020 having undergone knee surgery last year.

The 20-time grand slam champion opted not to play in Australia this year but is aiming to return in Doha in March.

"I want to celebrate great victories again. And for that I am ready to go the long, hard road," Federer, a three-time champion at the tournament, said in an interview with SRF.

"I wanted to make my comeback at a smaller tournament so that I wasn't fully in focus and where the stress is also a little less."

Federer said it "hurts" to miss out in Australia but still has lofty ambitions at Wimbledon, the Olympics and the US Open in 2021, while saying he will attempt to play on clay this year.

"I'll try to play on clay again. The whole thing, of course, with regards to Halle, Wimbledon, the Olympics and the US Open," he added.

Federer's on-court rival Nadal matched the Swiss for most grand slam singles titles won by a male player after winning the French Open last year.

But his chances of going one better may be hindered by a back issue that forced the Spanish great to sit out his country's ATP Cup opener against Stefanos Tsitsipas on Tuesday.

"Hi all, we have decided with #TeamSpain and my team, to not play today the first match of the @ATPCup here in #Melbourne since I have a stiff low back. Hopefully I'll be better for Thursday," Nadal posted on Twitter.

Roger Federer decided to miss the Australian Open because wife Mirka opposed having to spend a full fortnight in quarantine, a leading official has claimed.

It was widely assumed Federer's reason for skipping the upcoming grand slam related to the knee surgery he underwent last season.

He had hinted as much, and agent Tony Godsick referred to the knee rehabilitation when announcing in December that the Swiss great would not travel to Melbourne.

But Andre Sa, the head of player liaison at Tennis Australia, says Federer pulled out when it became apparent his wife and children would be holed up in their hotel accommodation for two weeks.

The players travelling to Australia must all quarantine to avoid any possible spread of COVID-19, but they are allocated five hours per day in which they can leave their rooms to train and practise with specified hitting partners.

Sa, a former top-20 doubles player, told Band Sports in his native Brazil that he discussed with father-of-four Federer the practicalities before the 20-time grand slam winner reached his decision.

"The main reason was the quarantine," said Sa. "I talked to him a month ago and he had two options. He could come with the whole family and do the quarantine.

"The problem is that Mirka and her children couldn't leave the room. They would have to stay 14 days in the room. The exception is only for players.

"He could go out, train and come back, but the family couldn't. Mirka did not approve the idea.

"The other option would be for him to come alone. Only there would be at least five weeks away from family and children. And then he said, 'Dude, 39, four kids, 20 grand slams. I'm no longer at the stage to be away from my family for five weeks.'"

Former world number one Federer has not played a tournament since losing to Novak Djokovic in the semi-finals of the Australian Open last year.

This year's edition of the grand slam has been delayed by three weeks to a February 8 start, due to factors tied into the pandemic.