World No 4 Radwanska shocked by Robson

The 19-year-old Briton matched the world No 4 in the opening stages of the match before she changed gears and demolished her Polish opponent’s serve to win convincingly, 6-3 6-1.

It is one of the biggest wins of Robson’s career and she will now face either Ana Ivanovic or qualifier Chanelle Scheepers, who play their second round game today.

The first set went on serve until the eighth game when Robson broke Radwanska after the 24-year-old netted a forehand to give the Briton a 5-3 lead.

Robson then claimed the set with a wide serve and thumping forehand winner before she broke Radwanska immediately in the second set to stamp her authority on the match.

The Pole hit back with a break of her own to level things up but Robson, ranked 41 in world singles, snatched back the lead with the third successive break of serve as Radwanska started to use the drop shot as an offensive weapon.

Robson then held her own serve to move 3-1 ahead before she took her opponent all the way in the next game, eventually beating her to lead 4-1.

Radwanska, under huge pressure after losing four consecutive service games, was unable to derail Robson’s charge as the Olympic mixed doubles silver medallist powered to a 5-1 lead.

It meant that Radwanska, who was runner-up at Wimbledon last year, had to serve to stay in the match.

She was unable to do so, as Robson claimed her fifth break of serve to win in one hour and 13 minutes.

Tennis authorities have opened an investigation following allegations that Australian player Bernard Tomic’s father John was involved in an altercation with his son’s hitting partner Thomas Drouet in Madrid.

The ATP has confirmed that an incident took place but did not give any more details.