While Novak Djokovic is expected to dominate at the Australian Open, which begins at Melbourne Park on Monday, questions remain over Serena Williams.
World number one Djokovic started 2016 in similar fashion to the way he finished last year, winning a title.
The Serbian took out the Qatar Open crown in Doha in an ideal start to his campaign, with his stunning performance in the final against Rafael Nadal drawing particular praise.
Djokovic dismantled the Spaniard 6-1 6-2 in a stunning display that sent a message to his rivals and extended a remarkable sequence of results.
He has also been given a kind draw, with Kei Nishikori his likely quarter-final opponent at Melbourne Park.
Nadal, whose quarter includes 2014 champion Stan Wawrinka, seemingly has a lot of work to do to close the gap to Djokovic.
Wawrinka was the only man standing between Djokovic and a Grand Slam last year, thanks to the Swiss' win at the French Open.
He has enjoyed Melbourne and along with Andy Murray appears the most likely to challenge Djokovic.
The Brit opens against Alexander Zverev, a talented German he beat in straight sets at the Hopman Cup.
Roger Federer will bid to add to his 17 grand slam titles and Czech Tomas Berdych is the highest ranked player in his quarter.
While Djokovic appears close to unbeatable, matters are slightly different for Williams.
The American world number one has battled a knee injury in the lead-up to the year's first grand slam.
Williams, a 21-time major winner, went close to taking out the Grand Slam in 2015, only to miss out at the US Open.
The injury worry and her lack of competitive matches shape as a concern ahead of a first-round clash against hard-hitting Italian Camila Giorgi.
However, a woman she has dominated in Maria Sharapova is in her quarter, meaning there could be a repeat of the 2015 decider.
The women's draw has threatened to be decimated by injuries and illness.
Joining Williams in being under a cloud are Simona Halep (Achilles), Garbine Muguruza (feet), Agnieszka Radwanska (leg), Maria Sharapova (arm), Petra Kvitova (illness) and Angelique Kerber (illness).
Halep has appeared in decent form despite her concern, with her run at the Sydney International particularly impressive.
This shapes as a huge chance for the Romanian to claim her maiden grand slam, having been runner-up at the 2014 French Open.
Williams remains the one to beat if she is fit, but Djokovic appears in even better shape.