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.