British teen sensation Laura Robson is riding a wave of confidence and says her gruelling Australian Open upset of world number eight Petra Kvitova was one the best, and toughest, of her career.
The 18-year-old kept her composure in a 94-minute third set as the 2011 Wimbledon champion lost hers in a three-hour match that finished in the early hours of Friday morning, winning 2-6, 6-3, 11-9.
It builds on a breakthrough 2012 for Robson, who defeated Kim Clijsters and Li Na during an impressive run to the US Open fourth round, and won Olympic silver in the mixed doubles with Andy Murray.
She also became the the first British woman since Jo Durie in 1990 to reach a main tour singles final, at Guangzhou in China in September.
"I thought against her was pretty ugly, but in terms of how tough it was to close it out in the end, I think it's right up there with one of the best wins," she said.
Robson, ranked 53, now plays another teen, American Sloane Stephens, to match her US Open fourth round achievement.
If she gets through that, she could face Kimiko Date-Krumm, 42, with the ageless Japanese veteran making her Grand Slam debut five years before Robson was born.
The Briton said she was aiming high this year.
"This year I set my expectations a bit higher, and I'm obviously playing a lot better than I was then (last year), so I would have been disappointed to lose today," she said, adding that she had always had a fighting spirit.
"I'd like to think so. Definitely when I played my brother in Monopoly it was -- all hell broke loose," she joked.