Garbine Muguruza, 22 (Esp)
World No. 2. Grand Slam titles: 1
Big-hitting Muguruza announced her arrival as a major force with a surprise straight-sets victory over Williams in the French Open final for her maiden Grand Slam triumph earlier this month.
Despite struggling to adapt to grass early in her career, Venezuela-born Muguruza knows what it takes to thrive at Wimbledon after an unexpected run to last year's final, which included four wins over higher-seeded opponents, before losing to Williams in the title match.
Agnieszka Radwanska, 27 (Pol)
World No. 3. Grand Slam titles: 0
Radwanska, a self-confessed tennis junkie who winds down by watching more of the sport on television in her hotel room, is desperate for a Grand Slam breakthrough, and Wimbledon may represent her best opportunity.
After winning the junior title in 2005, Radwanska reached her only Slam final at Wimbledon four years ago, but was beaten by Williams in three sets.
She also made the semi-finals in 2013 and 2015 to give her encouragement after an erratic 2016.
Angelique Kerber, 28 (Ger)
World No. 4. Grand Slam titles: 1
Just six months after stunning Williams to win her first major title at the Australian Open, Kerber finds herself back at a career crossroads.
The German, who had made only two Slam semi-finals before this year, hoped her success would serve as a springboard for greater success after a long spell labouring in obscurity.
Instead she has reverted to her inconsistent ways, losing in the first round of five tournaments since then. Still, she should not be overlooked.