Tennis players work for years to climb up the rankings.
But sometimes the form book can whizz right out of the window.
A hungry up-and-comer...a long-standing rival...a great reliving her glory years.
The prospect of lifting a trophy, or breaking a record, or representing one's country can inspire players to unexpected feats of achievement - so the best players in the game always need to be on their guard against a shock.
Check out our compilation of the Top 10 biggest upsets of the last decade!
