Second seed Elina Svitolina was the biggest casualty on day one of the WTA Istanbul Cup.

The Ukrainian was bundled out in straight sets by Magdalena Rybarikova, the 20-year-old going down 6-1 6-3.

Daria Gavrilova, seeded sixth, also fell at the first hurdle, battling back to level with Lesia Tsurenko after losing the first set in a tie-break, only to slump in the decider as Tsurenko ran out 7-6 (7-2) 3-6 6-3 victor to potentially set up a second-round clash with top seed Venus Williams.

And Anastasia Pavlyuchenkova made it three seeds making an early exit, as she crashed to a comprehensive 6-2 6-1 loss to last year's beaten finalist, Roberta Vinci.

Monday's final first-round clash saw Bojana Jovanovski down Yaroslava Shvedova 5-7 6-3 6-4.