Germany's Julia Goerges has booked her place in the second round of the women's Olympic singles with a three-set victory over Polish second seed Agnieszak Radwanska.
Goerges broke her opponent instantly in the opening set before Radwanska levelled with a break of her own. However, the world number 24 broke again to take the first set 7-5.
With neither player dropping a service game in the second, Wimbledon finalist Radwanska got herself firmly back in the match with a 7-5 victory in the tie-break.
In an up-and-down decider, Goerges looked to be on her way out of the tournament when she was broken, but she came back to break twice and see out the match 6-4.
She will now face either American Varvara Lepchenko or Paraguay's Veronica Cepede Royg in the second round.
