Top seed Danielle Collins suffered a shock defeat in a marathon first-round match with Simona Waltert at the Ladies Open Lausanne.

Collins, ranked a career-high seventh in the world, lost to a player 147 places below her as home hope Waltert prevailed in a final set tie-break.

The American battled back from a break down three times in the final set and had three match points in the tie-break.

But Collins could not find the telling blow as Waltert improbably turned the tide to win five successive points, and claim her first top-10 win 6-7 (5-7) 6-3 7-6 (8-6) after three hours and one minute of play.

Meanwhile, Waltert's compatriot Belinda Bencic survived a scare to avoid joining Collins on the casualty list, recovering from a set down to beat Diane Parry 3-6 6-3 6-1.

World number 77 Parry has claimed notable recent scalps in former French Open champion Barbora Krejcikova at Roland Garros and Kaia Kanepi at Wimbledon, but was denied another as the second seed hit back to advance. 

But there was no joy for fifth seed Nuria Parrizas-Diaz, who suffered defeat to Petra Martic, while eighth seed Varvara Gracheva lost to qualifier Eva Lys.

However, third seed Irina-Camelia Begu overcame Tamara Korpatsch in straight sets and sixth seed Caroline Garcia - fresh off a fourth-round run at Wimbledon - defeated Jasmine Paolini 6-3 6-3.

At the Hungarian Grand Prix, second seed Martina Trevisan came from a set down to survive against Natalia Szabanin and third seed Yulia Putintseva and ninth seed Anna Bondar also prevailed.