Jessica Pegula has upset world No.1Iga Swiatek to give the USA a surprising and significant early lead over Poland in the opening United Cup semi-final in Sydney.
Pegula reversed a run of four straight losses to Swiatek with a commanding 6-2 6-2 victory over the reigning French and US Open champion and hot Australian Open favourite.
Hardly a slouch herself after rising to No.3 in the rankings following a stellar 2022 campaign, Pegula never blinked under a closed roof at Ken Rosewall Arena.
Pegula broke Swiatek five times and dropped her own serve only once in storming to her first win over the three-time grand slam champion since 2019.
Now undefeated in three singles and two mixed doubles matches at the inaugural United Cup, Pegula's latest win gives the US a 1-0 lead in the best-of-five-match tie.
US Open semi-finalist Frances Tiafoe is a hot favourite to beat Kacper Zuk in Friday's men's singles to ram over Team USA's advantage ahead of Saturday's remaining three rubbers.