World number one Andy Murray insisted Sunday that Novak Djokovic will remain his biggest threat in 2017, as the pair prepare for a potential first clash of the season in Doha this week.
Newly-knighted Murray, speaking ahead of the first round of the Qatar Open which begins on Monday, said the Serb would continue to make life tough for him on court this year.
"In terms of the number one ranking, Novak would be (the biggest threat)," Murray told reporters.
"I had a great sort of four, five months at the end of last year and I still only got to number one by one match basically at the end the year, so I know it will be very tough to stay there."
Murray also tipped six-times Australian Open champion Djokovic to be the player to beat in Melbourne, when the year's first Grand Slam begins later this month.
In Qatar, Murray is the number one seed and if matches go to form it will set up a mouth-watering final clash with Djokovic, the number two seed and defending Doha champion, on January 7.
Murray's first round match is against France's Jeremy Chardy on Tuesday.
Djokovic begins his title defence on Monday against Germany's Jan-Lennard Struff.
At this stage last year, Djokovic was dominating men's tennis and there was much talk of him winning all four Grand Slams in 2016.
But despite winning in Australia and the French Open, Djokovic's season tailed off in the second half of the season, which saw him crash out in the third round at Wimbledon and losing the US Open final to Stan Wawrinka.
But he denied on Sunday that his game was in "crisis".
"I don't see the six months, second six months of 2016 as a failure or anything like that," he told reporters.
"It's not in my mindset, I guess, in my philosophy of life to observe things in this way -- that I didn't succeed, that I failed, that I've fallen or something like that.
"I just feel like every experience is a blessing one way or another."
The 12-times Grand Slam winner and former world number one added that he retained his hunger to win.
"Without a doubt, when I'm on the court there is no other thing than to win that tennis match."
Despite Murray and Djokovic getting top billing in Doha, they are unlikely to get things all their own way this coming week.
Also playing is one of last year's semi-finalists, Tomas Berdych, this year's number three seed.
France's dangerous Jo-Wilfried Tsonga is the number five seed and he has beaten Murray and Djokovic a total of eight times in his career.
The Qatar Open, now in its 25th year, has not been successfully defended since Murray won back in 2009.