Prague,  No.1 seed Simona Halep was made to toil hard in the opening round of the Prague Open as she eventually edged out Slovenia's Polona Hercog 6-1, 1-6, 7-6(3).

The Romanian needed seven match points in a match that lasted for two-and-a-half hours on Tuesday as both players fired 29 winners while Help made less mistakes, 39 against Hercog's 42.

"I knew it was going to be difficult," said Halep as quoted by the official WTA website. "All our matches were very tough and very long," recalled Halep.

"She knows me pretty well, we played in juniors. She changes the rhythm, she plays dropshots, a little bit softer then harder, so it was tougher for me to be in the point."

Meanwhile, No.2 seed Petra Martic bounced back from disappointment at the weekend to open her campaign by edging Varvara Gracheva 7-6(2), 6-3 in one hour and 50 minutes.

Martic took a medical timeout between sets on Tuesday but eventually won the match.

"Not an easy one, especially the first set," said Martic after the culmination of the match. "Unfortunately couldn't serve it out, but I'm happy I brought my level up in the tiebreak where it mattered."

Her physical state, she said, was more of a question of maintenance than anything serious. "It's definitely not ideal - I have some aches here and there, the body is still adjusting to matches and playing one after another - but I think it's normal and I hope I can maintain it to last this tournament," she added.