Birmingham - Angelique Kerber's chances of clinging to a small lead at the top of the world rankings may hinge on the quality of her performances at the Birmingham WTA grass court event starting Monday.
They may also have a crucial bearing on Kerber's ability to challenge for the title at Wimbledon which begins in a fortnight's time, as she makes the often tricky transition from clay to grass courts at the $800,000 Premier level event.
The signs do not appear good for the 29-year-old Poland-born German, even though she been number one much of the time since September.
She has yet to capture a title this year and none of her 21 wins in 11 tournaments have been against a top 20 opponent.
Nevertheless Kerber is significantly more effective on grass than on clay, and won her first title on the speedier, lower-bouncing surface in Birmingham two years ago. She went on to reach the Wimbledon final last year.
Another good run at the tranquil, tree-lined Edgbaston Priory Club, with its leafy affluence and well-manicured courts, may be within her capacity, and if so it could work wonders for wavering confidence.
Although Kerber often says that protecting a ranking and coping with pressure are issues she tries to keep from her mind, there is little doubt that a few wins and some lengthy court time would be very timely.
"I always look forward to grass," she emphasises. "And I really like playing here."
Kerber comes into the event still smarting from becoming the first top seed to lose in the opening round at Roland Garros.
She has also landed a potentially difficult draw.
Her opener is against Lucie Safarova, the 2015 French Open finalist from the Czech Republic, and there is a possible quarter-final against the fifth seeded Kristina Mladenovic, the French woman who spectacularly halted Garbine Muguruza's French Open title defence.
If Kerber does make the final her opponent, according to the seedings, should be Elina Svitolina, who captured the Italian Open title last month and has prevailed in both her encounters with Kerber this year.
However two notable withdrawals after their French Open exertions are Simona Halep and Karolina Pliskova, and they are Kerber's closest rivals for the number one ranking.
Her capacity for taking advantage of these absences may depend on how well her fitness holds up, for adaptations in shot-making on grass which require a lower centre of gravity, can bring new physical stresses.
Kerber retired with a thigh strain against Eugenie Bouchard in the third round in Madrid last month.
Meanwhile there will also be focus on Petra Kvitova, the trenchant left-hander who has twice been the champion at Wimbledon.
Grass is by far Kvitova's best surface and she should enjoy returning to it.
However the most she will probably aspire to is continued rehabilitation from career-threatening hand injuries suffered during a horrendous knife attack by an intruder at her home last year.
The likeable Czech has been able to play only two matches this year, and even modest progress this week may earn sympathetic acclaim and hopes that, at the age of 27, she might yet resurrect her career.