Johanna Konta is aiming to become the first British woman since 1983 to reach the French Open semi-finals - and her Fed Cup coach Anne Keothavong says she has yet to hit her peak.
Konta, 28, meets seventh seed Sloane Stephens, last year's runner-up, in Tuesday's quarter-final at 13:00 BST.
The Briton had never won a main-draw match at Roland Garros until this year.
"A lot of things are coming together but she can go up a few more levels if pushed," Keothavong told BBC Sport.
"Jo has played some fantastic tennis and the best thing is she can play even better - she is still very much playing within herself.