Elina Svitolina and Simona Halep both fell in the first round of the Qatar Ladies Open, while Garbine Muguruza and Anett Kontaveit eased through on Monday.
Former world number one Halep, champion in Qatar back in 2014, was off the pace as Caroline Garcia claimed just her second win in nine meetings against the Romanian with a 6-4 6-3 triumph.
Number 10 seed Svitolina also suffered an early exit after ending up on the wrong side of an almost three-hour slog, with Tereza Martincova eventually succeeding 6-7 (2-7) 7-5 7-6 (7-5).
But fifth favourite Muguruza – a two-time finalist, including in 2021 – did not have much as trouble as she outfought Sorana Cirstea 7-6 (7-4) 6-1 in a second-round contest, with Kontaveit coasting through to round three in similar fashion with a 6-2 6-3 win over Ana Konjuh.
Jelena Ostapenko, who is a former finalist in Doha and champion in Dubai last week, managed a sixth consecutive victory in the Middle East as she downed Oceane Dodin 6-4 6-2 to reach the second round, while 11th seed Elena Rybakina fell at the first hurdle to Jacques Cristian in a 6-4 6-3 loss.
Angelique Kerber, the 13th ranked player at the tournament, was another surprise first-round loser as she fell 4-6 6-3 6-2 to Jil Teichmann.
Cori Gauff secured her spot in the second round with a straightforward 6-2 6-3 victory over American compatriot Shelby Rogers, while 16th seed Elise Mertens battled to a 6-3 2-6 7-5 win over Jasmine Paolini.
Meanwhile, defending champion Petra Kvitova had no trouble easing past Irina-Camelia Begu 6-3 6-1, and Daria Kasatkina edged out Ajla Tomljanovic 6-4 6-7 (4-7) 6-2.