Heather Watson's impressive form at the Indian Wells tournament in California continued yesterday, with what must surely rank as the biggest win of her Tennis career so far. Her brilliant success in the third round of the BNP Paribas Open event was confirmed with a 6-4 6-4 victory over the world number eight seed, Agnieszka Radwanska. It was the first time that she had ever beaten a player ranked in the top ten and must surely give her renewed confidence, not only for the rest of this event, but also going into the summer challenges to come at the French Open and Wimbledon, where she must surely now be looking to go further than the third-round best she has so far achieved.

The 22-year-old was in a positive mood from the start against her better established opponent, breaking the Polish woman's service twice after dropping her own serve early on. After utilising her double-handed backhand to good effect during the exchanges, she completed a solid first set performance with a sizzling ace to claim the set 6-4.

It didn't take her long to snatch an early advantage in the second set as well, breaking to go 2-0 ahead. Radwanska is a seasoned professional these days though and fought back to move into a 4-2 lead of her own, as the match seemed to be going her way after a slow start. Rather than knocking her back though, Watson responded to the challenge admirably to reel off four straight winning games of her own to clinch a well-deserved success.

Watson would have been slightly wary of her rival's abilities no doubt going into the match, having never previously taken a set off the 26-year-old at the other side of the net. She also had the unenviable record of failing to defeat a top ten player after 11 attempts on the WTA tour.

A delighted Watson told the BBC afterwards: "I knew I had the tennis in me but I needed the belief."

The matches will not get any easier for the Guernsey women from now on though, with another daunting match against Carla Suarez Navarro, the number 12 seed from Spain, next up for her.

Elsewhere in the women's draw, world number one seed Serena Williams stayed on course for the title with a comprehensive 6-2 6-0 demolition of Zarina Diyas of Kazakhstan, to join Watson in the last-sixteen. Her next opponent will be another American in the shape of the dangerous Sloane Stephens. After barely breaking into a sweat during the 53-minute 'exhibition' of her talents, she is clearly beginning to feel more at home at an event that she had boycotted since triumphing in 2001. She echoed that sentiment afterwards with: "It definitely felt back to normal out there."