Johanna Konta saves best form for grand slams after reaching US Open last-16

British No 1 could face a semi-final clash with Serena Williams, who reached the fourth round with a routine win over Karolina Muchova

Johanna Konta beat Shuai Zhang to reach the US Open fourth round. AFP

Johanna Konta has said she cannot explain why she performs better at grand slam tournaments compared to the rest of the year after reaching the US Open last 16 on Friday.

Konta, the 16th seed, produced an impressive display to defeat Chinese 33rd seed Zhang Shuai 6-2, 6-3 in one hour and 12 minutes.

The result equals the British No 1's 2015 and 2016 runs to the fourth round in New York and she will play former finalist Karolina Pliskova for a spot in the quarter-finals.

Konta has experienced middling fortunes on the WTA Tour circuit this season while producing some of her best tennis at the majors, reaching the semi-finals at Roland Garros and then advancing to the last eight at Wimbledon last month.

Konta's best non-major result came at the Rome Masters in May when she reached the final before losing, incidentally, to Pliskova.

"I don't think there's necessarily any specific magic click or pill or anything, but I definitely feel like I've been giving myself every opportunity possible to get better and grow," Konta said.

"I don't think I necessarily allowed losing in the first round of Toronto or Cincinnati really to discourage me in any way."

Konta is enjoying a resurgence at Flushing Meadows, where she crashed out in the opening round on her past two appearances.

"I'd like to do even better at slams obviously. But I think I'm definitely pleased to have made it to the second week of the last three slams. I think that's a really good achievement for me," she said.

"I think I've had some pretty good results outside of slams, as well.

"If I look at it from a big-picture perspective, I've played a lot of matches this year," she said. "I think coming into US Open this year I just tried to keep along the same path more than anything."

A three-time semi-finalist at the majors - one each at the Australian Open, French Open and Wimbledon - Konta's hopes of landing her first grand slam title could hinge on overcoming six-time champion Serena Williams.

Placed in the same half of the draw, Konta could meet Williams in the semi-finals, and the American produced an ominous display to beat Wimbledon quarter-finalist Karolina Muchova 6-3, 6-2 on Friday.

"Had to go out there on business," Williams said in her post-match press conference. "I think I tried to do that with all three matches thus far. It was just different because I know that [Muchova] could play today. I knew what she could do."

Williams, seeded eighth, next faces 22nd seed Petra Martic, before a potential clash with second seed Ashleigh Barty, as long as the Australian gets through her match against Chinese 18th seed Qiang Wang.