Bulgaria's Tsvetana Pironkova pulled off a surprise win against illness-hit U.S. No. 2 Varvara Lepchenko at the Kremlin Cup on Tuesday.
Slow-starting Lepchenko was swept off the court in the first set, but went a break up in the second before Pironkova reeled her in and won the match on the tiebreak for a 6-0, 7-6(3) win.
"I started really well. My serve was going really well, all my shots were just in the place where I wanted them to be, Pironkova told R-Sport.
Lepchenko blamed illness for the early exit at her last tournament of the season.
"I wasn't feeling that great the whole week and the previous week," she said.
"I tried the best I could but unfortunately it didn't show any results today. I was struggling with my sleep, with breathing and it showed."
Pironkova, ranked 23 places below Lepchenko at No. 44, faces either reigning champion Dominika Cibulkova or Russia's Ekaterina Makarova in the second round.
"I've played against both of them, really tough opponents," Pironkova said.