(7) Sara Errani
Errani entered 2012 ranked 45 in the world and regarded as little more than a solid campaigner but just 12 months later she's catapulted herself into the top 10 following an astonishing breakthrough year.
It all started this time last year when the Italian reached the quarter-final stage of a grand slam for the first time in her career at Melbourne Park but that was only a sign of bigger things to come.
Despite not winning a WTA title since claiming two in 2008, the claycourt specialist then triggered an impressive run of success by defeating Flavia Pennetta in the final of the Mexican Open in Acapulco back in March.
Two more titles followed on her favourite surface in Barcelona and Budapest over the course of the next two months, putting her into a strong position heading into the French Open.
And the 25-year-old used this momentum to great effect at Roland Garros, where she was only defeated in the final by Maria Sharapova after enjoying the best run of her career so far.
The diminutive Errani, who did claim the French Open doubles title alongside compatriot Roberta Vinci, was knocked out in the third round at Wimbledon but swiftly bounced back in her next event to claim the WTA title in Palermo on clay.
A semi-final run at Flushing Meadows capped a year to remember and don't be surprised if this Italian raises more eyebrows in 2013.