Rafael Nadal and Novak Djokovic lead the Qatar Open field from Monday while, 12,000km away in Brisbane, Roger Federer starts his 18th year on the tour as tennis heads for another gripping season.
The details of Nadal's plan to preserve his hopes of one day becoming the most successful player of all time may become clearer when he starts his title defence at Qatar.
Although the Spaniard is almost five years younger than Federer, and is only three Grand Slams behind his all-time record of 17, changing his goals and his schedule will be vital if he is to surpass the Swiss genius.
After an appendectomy cut short a 2014 season which also brought problems with his back and wrist, Nadal has accepted that stringent compromises are required.
The wear and tear of more than 850 matches has left Nadal unable to sustain intense physical pressure for long periods, and has caused him to give up ambitions of ever again being world number one.
"That won't be a goal in my career any more," says Nadal, who is currently ranked three behind Djokovic and Federer.
"If I become number one because of my results, then great. But I'm not going to pursue this objective. Instead I will follow my schedule."
That is because, well into his 29th year, Nadal is making one of his greatest goals to play as many remaining years as possible.
"What I won't do is put at risk the best years of my career to get the number one spot," he emphasised.
This was a policy Federer adopted a couple of years ago, something which has helped him, at 33, to remain a serious contender.
Preserving his physical condition is a precondition for Nadal preserving his career as well, though he has mental repair work as well.
After missing the whole of the 2014 American hard court season and not competing since October 24, the effect of these absences is important.
"It wasn't a negative season in terms of all results, it was negative in terms of mentality because it was hard to accept that I wasn't able to compete for the whole year," nine-time French Open champion Nadal conceded.
"There are only two or three weeks left for the Australian Open and I hope to arrive there feeling well, but I'm aware two weeks might not be enough to be back at a hundred percent."
The Doha seedings suggest he should face world number one Djokovic in Saturday's final, but a fever caused the world number one's withdrawal from the final of the weekend exhibition event in Abu Dhabi.
It remains to be seen whether he recovers enough to make his first appearance in Doha.
- Djokovic eyes French Open -
Djokovic, who picked up his seventh major at Wimbledon in 2014, became a father only three months ago and has been taking advice from Federer on how best to cope with having a family on tour.
The only thing which has prevented the 27-year-old Serb from joining Federer and Nadal in the career Grand Slam club is the absence of the French Open title, the rectifying of which has become his biggest career goal.
He will try again at Roland Garros in May and June by which time both Djokovic's state of mind and Nadal's physical fitness may be better understood.
Federer, meanwhile, continues to confound the doubters.
The Swiss great was runner-up to Lleyton Hewitt in last year's final in Brisbane and should he win four more matches this week and lift his 74th tour-level title, he would become just the third player in the Open Era to reach the 1,000 match wins milestone after Jimmy Connors (1,253) and Ivan Lendl (1,071).
World number two Federer compiled an ATP World Tour-best 73-12 match record in 2014, including five titles, and helped Switzerland win a first Davis Cup crown.
"I was consistent and I was playing positive, attacking tennis, the exact way I want to play. I gave myself quite a few chances at the Slams. I want to go one step further, because being close is not quite good enough," he said.
Andy Murray has slid to world number six since winning the 2013 Wimbledon title and undergoing a back operation which probably left him a small but crucial percentage short of physical strength.
The signs were good at Abu Dhabi where Murray won the title, having beaten Feliciano Lopez and trouncing Nadal for only two games.
Murray has dispensed with two long-time allies, hitting partner Dani Valverdu and fitness trainer Jez Green, kept Amelie Mauresmo as coach when some predicted her dismissal, and seems about to add more French back-up in the person of Loic Courteau.