Serena Williams' bid to extend her phenomenal career into her 33rd year will take a tentative but crucial step forward when she unexpectedly lines up at the head of the field for the Dubai Open which starts on Monday.
Tennis' iconic female had planned to give the popular and lucrative tournament a miss until a back injury at last month's Australian Open altered the shape of her year. She needs to prove that it won't alter the shape of her career either.
Serena has already confounded countless predictions by recovering from a hematoma and a life-threatening pulmonary embolism, and improbably regaining the world number one ranking a year ago. But injuries at this age, especially back injuries, can be a cause for anxiety.
She is however making a decent job of trying to dispel that. She twittered a message this week precisely designed to show how vigorous she feels she is.
"Hit today with not sure if he will want to hit with me again cauz I'm Crazy intense on practice court," it read, making a jokey reference to her French coach, Patrick Mouratoglou.
But practice is one thing and hard matches on hard courts after an absence are quite another. Serena will be seeking reassurance about her fitness, and, almost as vital, match practice.
Had she not accepted this last minute wild card and been prepared to travel to the Middle East she would have had gone two months without competition.
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She withdrew from this week's Qatar Open because of the bad back, declined on principle to play at Indian Wells, and was scheduled to appear next at Miami in mid-March.
All that follows two months of the off-season. Without Dubai, Serena would have played only eight matches in four and a half months. Good as she is, that would have been risky if she aims to win big titles.
The 32-year-old American has never won the title at Dubai and has not appeared there since 2009, where she lost to elder sister Venus Williams in the semi-finals. Venus has also taken a wild card into Dubai.
Serena is seeded for a final with Agnieszka Radwanska of Poland which would be a repeat of the 2012 Wimbledon final.
She could start against Ekaterina Makarova, the Russian who recently won the Pattaya title, and might have a semi-final with Petra Kvitova, the former Wimbledon champion against whom she recovered from 1-4 down in the final set to regain the world number one ranking after a two-year interval this time last year.
Venus, who held a match point against Kvitova this week in nearby Doha and articulated an enduring ambition to win big matches, also starts against a Russian, Elena Vesnina.
Her reward for winning would be a meeting with Angelique Kerber, the sixth seeded German, or Ana Ivanovic, the former world number one from Serbia who beat her in the Auckland final last month.
The immediate future for both sisters is uncertain. The medium term for Serena includes a desire for one more Grand Slam title, her 18th, which would put her level with the totals of Martina Navratilova and Chris Evert, and four behind Steffi Graf's professional era record.
And in the long term Serena has already hinted that she wants to play at the 2016 Olympics in Rio and therefore to be around for at least another three years. Next week may offer hints into how likely that still is.