Top seed Jelena Jankovic fell 5-7 6-3 6-3 to world No.17 Flavia Pennetta in the second round of the Tennis.com Zurich Open and lost her first in 13 matches.
Pennetta has never before beaten Jankovic, and they had played five times before this Zurich meeting. Additionally, the 26-year-old Italian today defeated a number one player in the world for the first time.
Jankovic, who won three straight titles heading into the Tennis.com Zurich Open, beat Pennetta in straight sets last week at the Kremlin Cup after the Italian had knocked out Venus Williams.
The Serb has never made it past the second round at the Zurich Open in four tournament appearances.