Iga Swiatek believes she is growing into the US Open and improving with each day that passes after storming into the quarter-finals by beating Liudmila Samsonova.
Five-time grand slam winner Swiatek is hunting her second title at Flushing Meadows, and she will face home favourite Jessica Pegula in the last eight after overcoming Samsonova 6-4 6-1.
She needed just over an hour and a half to see off the 16th seed on Monday in what represented her 100th main-draw match at grand slams.
Among those to begin their careers in the Open Era, only six female players have bettered Swiatek's total of 83 victories through their first 100 major outings.
Monica Seles managed 93 wins, putting her ahead of Chris Evert (90), Steffi Graf (87), Martina Hingis, Serena Williams (both 86) and Venus Williams (85).
Swiatek is also one of just four players in the last two decades to win 12 straight grand slam matches versus WTA top-20 opponents, alongside Graf, Seles and Serena Williams.
She still believes there is more to come, though, as she approaches Tuesday's headline tussle with sixth seed Pegula.
"At the beginning, I felt like we were playing men's style, just holding our serves but I knew that if I kept pushing I may get some chances to break," Swiatek said.
"That happened and I'm happy I was there to close the first set. Then I just wanted to keep being focused and not let my mind drift off.
"I'm happy with the whole performance. I'm feeling better and better every day."
The victor of Swiatek's meeting with Pegula will face Karolina Muchova or Beatriz Haddad Maia for a place in the final, after the former upset Jasmine Paolini and the latter overcame Caroline Wozniacki.
Haddad Maia's' 6-2 3-6 6-3 win over Wozniacki – who won the 2018 Australian Open – made her just the second South American woman to claim multiple US Open victories over former grand slam winners (two), alongside Argentina's Gabriela Sabatini.