Simona Halep's roller-coaster season came to a welcome halt on Thursday when a crushing first set tie-breaker against Agnieszka Radwanska at the WTA Finals.
Russian Agnieszka Radwanska battled her way past Romanian Simona Halep in the WTA finals as she set herself up for a semi-final match against Pennetta.
Spain's Garbine Muguruza moved to the brink of the WTA Finals last four with a 6-4 6-4 win over Angelique Kerber on Wednesday after Petra Kvitova opened her account with a 7-5 7-5 victory over fellow Czech Lucie Safarova.
Roger Federer bounced back to form with a quick-fire win over Mikhail Kukushkin as he began his bid for a seventh title at his hometown tournament in Basel.
When it come to tennis there is no greater prize than winning a grand slam singles title. Hree are some players who achieved this at an unbelievable age.