England's world number 231 Naomi Broady edged past highly-rated French teenager Caroline Garcia 6-2 6-7 6-4 to join Heather Watson in the second round of the Aegon Classic in Birmingham.
Broady, ranked 81 places lower than Garcia, cruised to the first set.
And despite losing the second on a tie break in a rain-affected match, she held her nerve to take the third.
Broady, 21, will play Britain's in the last 16 if they win their second round matches.
Stockport-born Broady managed to break Garcia - whom Britain's most prominent player, Andy Murray, recently tipped as a future world number one - with ease early on to take a well-deserved first set in 23 minutes.
After a rain break Broady served well under pressure to force a second set tie break, but Garcia's class told as she clinched it 7-5 with a big ace after being 0-2 down.
But her English opponent broke Garcia late in the third set, which Broady took clinically as the French youngster - who - marched off court at the Edgbaston Priory Club in anger.
Broady has been given a Wimbledon wild card invitation, as has Watson - now world number 93 - who
In other results on Tuesday in Birmingham, Australia's Casey Dellacqua beat the Czech Republic's Sandra Zahlavova 7-5 7-6 while Japanese ninth seed Ayumi Morita defeated Croatia's Ajla Tomljanovic 6-3 3-6 6-4.
Morita's fellow countrywomen Misaki Doi also beat Romania's Edina Gallovits, as Kazach 11th seed Yaroslava Shvedova eliminated China's Jie Zheng while Jill Craybas saw off Andrea Hlavackova.