Laura Robson feels she has earned her grand slam breakthrough after pulling off the result of the day for the second consecutive round at the US Open and subsequently becoming the first British woman to reach the fourth round of the US Open for 21 years.
The 18-year-old made it back-to-back wins over former grand slam champions on Friday when she added Li Na's scalp to that of Kim Clijsters with another stunning performance. Li has been one of the form players of the north American summer but was outplayed by the world number 89, who powered to a 6-4 6-7 (5/7) 6-2 victory.
Robson said: "I have just worked hard over the last few weeks and I feel like I'm playing very well. I have had lots of tough matches against some very experienced opponents so, the way that I see it, it was time to start winning a few of them."
Ninth seed Li was lacking her usual consistency in the opening set and a half but stepped up her game towards the end of the second to take the match into a decider.
But Robson, who is now the first British woman to reach the fourth round of a grand slam since Sam Smith at Wimbledon in 1998 and the first at the US Open since Jo Durie 21 years ago, simply raised her level again and overpowered Li in the third set, and will now face defending champion Sam Stosur.
She said: "I had the opportunity to win it in two. It was a really close tie-break and at 5-5 she played two really good points. There's not much that I can do off that.
"I knew that if I kept playing the way that I was and kept playing how I started the first set, really aggressive and accelerating on my forehand when I had the opportunity, then I knew that she would struggle. That's what I did."
That Robson secured the win despite being on the wrong end of a couple of dubious umpiring calls was also impressive. The first incident came on break point in the fifth game of the third set when she hit a shot that landed on the baseline. It was called out and, although Robson's challenge was correct, she was made to replay the point and Li won it.
The same thing happened in the next game when a Robson serve was erroneously called out and again they replayed it, despite the British player's protestations.
Robson said: "I wouldn't say I wasn't distracted. I was a little bit annoyed. But that's what happens from time to time, so you've got to deal with it. I think being a little bit annoyed seemed to help me."