Rome - World No 1 Angelique Kerber crashed out of the Rome Masters on Wednesday, the top seed beaten 6-4, 6-0 in the second round by Anett Kontaveit of Estonia.
The German's 56-minute knock out came two days after she was confirmed at the top of the WTA rankings, displacing Serena Williams after making it to the third round at last week's Madrid Open.
The defeat demonstrated more of the patchy and inconsistent form which the 29-year-old cannot seem to shake off since starting to duel with Williams at the top of the WTA listings last season.
She lost serve five times to join another drawcard at the Foro Italico, Maria Sharapova, on the sidelines.
Results on the fourth day of the Rome Masters on Wednesday (x denotes seeding):
Men
Second round
Alexander Zverev (GER x16) bt Viktor Troicki (SRB) 6-3, 6-4
Milos Raonic (CAN x5) bt Tommy Haas (GER) 6-4, 6-3
Stan Wawrinka (SUI x3) bt Benoît Paire (FRA) 6-3, 1-6, 6-3
Dominic Thiem (AUT x8) bt Pablo Cuevas (URU) 7-6 (7/4), 6-4
Sam Querrey (USA) bt Jan-Lennard Struff (GER) 6-4, 6-3
Jack Sock (USA x13) bt Jirí Veselý (CZE) 6-4, 3-6, 7-6 (7/1)
Rafael Nadal (ESP x4) bt Nicolas Almagro (ESP) 3-0 - retired
Kei Nishikori (JPN x7) bt David Ferrer (ESP) 7-5, 6-2
Juan Martín Del Potro (ARG) bt Kyle Edmund (GBR) 7-5, 6-4
Roberto Bautista Agut (ESP) bt Pablo Carreño-Busta (ESP x15) 6-7 (6/8), 6-1, 6-4
Women
Second round
Anett Kontaveit (EST) bt Angelique Kerber (GER x1) 6-4, 6-0
Anastasia Pavlyuchenkova (RUS x12) bt Anastasija Sevastova (LAT) 7-6 (7/4), 6-2
Simona Halep (ROM x6) bt Laura Siegemund (GER) 6-4, 6-4
Ekaterina Makarova (RUS) bt Dominika Cibulkova (SVK x4) 1-6, 6-1, 6-3
Kiki Bertens (NED x15) bt Catherine Bellis (USA) 6-4, 6-0
Daria Gavrilova (AUS) bt Caroline Garcia (FRA) 7-5, 3-6, 6-3
Venus Williams (USA x9) bt Lesya Tsurenko (UKR) 6-4, 6-3
Julia Goerges (GER) bt Jelena Jankovic (SRB) 2-6, 7-6 (7/2), 6-1
Garbiñe Muguruza (ESP x3) bt Jelena Ostapenko (LAT) 2-6, 6-2, 6-1
Elina Svitolina (UKR x8) bt Alize Cornet (FRA) 6-4, 7-6 (13/11)
Mona Barthel (GER) bt Qiang Wang (CHN) 6-3, 6-4
Timea Bacsinszky (SUI) bt Barbora Strycova (CZE x14) 6-4, 6-2
Karolína Pliskova (CZE x2) bt Lauren Davis (USA) 6-1, 6-1