Former world No 1 Caroline Wozniacki was upset in the first round of the Italian Open by 48th-ranked Bojana Jovanovski 2-6, 6-4, 7-6 (5) on Tuesday.
Wozniacki wasted a 5-2 lead in the third-set tiebreaker. The Dane has struggled on clay this season, losing to Yaroslava Shvedova in the first round of last week's Madrid Open and to Carla Suarez Navarro in her first match in Stuttgart, Germany, last month.
In men's action, Mikhail Youzhny comfortably beat 13th-seeded Tommy Haas 6-4, 6-3 in a matchup of tour veterans.
Also, former top-10 player Fernando Verdasco of Spain outlasted Horacio Zeballos of Argentina 6-3, 3-6, 6-3.
Later, top-ranked players Novak Djokovic and Serena Williams, plus second-seeded Roger Federer, were in action.