Roger Federer, sounding content and looking fit as he returns to tennis after six months out through injury, predicted on Friday that Andy Murray and Novak Djokovic would continue to dominate the game in 2017.

“Whoever finishes [next year] as No1 is going to have to win two slams but it’s pretty much on Andy’s racket at the moment,” the Swiss said before leaving his Dubai training base en route to Perth for the Hopman Cup, which starts on New Year’s Day.

“Am I surprised Andy Murray is No1? No. I always expected him to be No1 at some point but finishing the year [in that position] is a different animal. I really respect Andy was able to get it done this way. It’s going to be hard for Novak the next few months [in defending ranking points] because of the domination he had at the beginning of 2016. I think Andy is going to hang on for a while but it’s going to be a neck-and-neck race for the next six months.”

Federer was for many years in that privileged position but the 35-year-old begins his 19th season on Tour at 16th in the ATP rankings, the first time since 2001 he has been outside the top 10. His chances of adding to his 17 majors are slim and he will do well to make the second week of the Australian Open, which starts in Melbourne on 14 January, but he seemed to be in good spirits after the longest layoff of his career.

He struggled for months with the effects of a freak injury in Melbourne a year ago when he twisted his knee while running a bath for one of his children, and resorted to surgery in March, the first such experience of his career. He fell heavily on his injured knee during his semi-final defeat to Milos Raonic at Wimbledon and has not played competitively since but he resumed hitting on court a month ago.

“The goal was to be fully fit by the end of November, early December,” he said. “We knew it was going to take a while to give the knee sufficient rest, not to hurry in the beginning. I went on vacation at the beginning of November for two weeks. The last few weeks have been crucial, to see how much load I can put on my legs. We quickly realised [when he resumed training] I wasn’t 100% but it went very well, no setbacks. It’s all great.

“The good thing about the layoff is I didn’t have to have surgery after Wimbledon, two surgeries in the same year. I just had to rest. I could play tennis, standing or walking – but I didn’t need to do it. Just before the US Open I had a bit of a reaction, so it was too early. It was always a great feeling to get on the court because I was spending a lot of time in the gym. It’s always refreshing to get back on the tennis court.

“I played well [in practice this month], struggling to find the serve but that is coming on very well. I might practise on the 26th and 27th, and fly to the Hopman Cup on the 28th. I finished my last [fitness] session two days ago with Pierre [Paganini]. In previous years, after a short off-season, I tried to pack in too much. Also it’s important to be around family and kids at Christmas.”

Federer denied the layoff had drawn him closer towards retirement. He said he had enjoyed the opportunity to relax at home with his wife Mirka and their four children – who will all be travelling to Australia with him.

“It’s not like I missed anything. It just felt right, the perfect way for me to take a rest for my body and my game. I’m always travelling with my family, always see them, but it was just nice to see them in one place. Nice to settle, get good routines for the kids. It felt good but also I cranked it up in the gym the last couple of months, It felt good to be busy. It was the right moment to have it.

“This year is unique. Maybe more than any time before I do need matches. There is a different intensity. I remember playing Hopman Cup against Lleyton Hewitt [in 2001] and was in pain for a week with muscle pain. I’ve played over 15 sets in practice the last few weeks and I feel I am there. It’s been a great preparation.”

Asked if the record $50m prize money on offer for the first major of the season in Melbourne suggested the game might direct more funds towards hunting down users of performance-enhancing drugs, Federer said: “It’s hard for me to tell but with all the money there is in the sport you would think there would be more anti-doping money. We’ve had issues in the past.

“I would like to see more funding, especially in the off-season; this is when the players work hardest. There are a few countries who test and other countries never test. We definitely could use more funding for all sports, not just tennis.”