Britain's Anne Keothavong enjoyed one of her best wins of the year against Ekaterina Makarova in Austria, but Elena Baltacha retired from her match.
Keothavong, ranked 96th, had lost in qualifying at the Generali Ladies event in Linz but picked up a lucky loser's spot in the main draw.
And she took full advantage by beating Makarova, the world number 53, 6-4 6-1.
Baltacha had a match point against world number 23, Dominika Cibulkova, but retired trailing 6-4 6-7 (3-7) 0-1.
The Scot later said on Facebook: "My back has been a bit tight this week, probably because this is my first tournament in a while, and I was concerned I was going to make it worse if I kept playing.
"I hate having to retire but you need to be 100% against someone as good as her. It's a shame because it was actually a really good match."
Keothavong goes on to face third seed Jelena Jankovic in the second round.
"Haven't been able to say this for a while but I actually played a good match today," Keothavong said on Twitter after her first-round win.