Martina Hingis survived a strong challenge to beat promising Russian Maria Kirilenko 7-5, 7-6 and reach the second round of the WTA event in Warsaw on Monday.
"Either way it would have been a great match," Hingis told reporters. "It was just very difficult conditions and today it was whoever had the stronger head and stayed in the match. One shot here and there and it could have been different."
It was Hingis's first match on clay in four years.
It's been a long time and it feels like it," she said.
"When you come from the hardcourt on to clay I think it's all up in the head. You have to be willing to be patient, a lot of rallies and a lot of hard work. But you also have time to try different variations. It takes time to find the strategy.
"At times I felt I was getting better. I started to figure out what to do on clay, but the movement is sometimes quite difficult," the Swiss added.
Her last opponent in a claycourt match was Venus Williams, who she should meet next, providing the American defeats Polish wildcard Urszula Radwanska.
That cannot be taken for granted, as it will be only the third match Williams has played since last September's U.S. Open.
She was beaten by unknown Bulgarian Tsvetana Pironkova in her only other match this year, at the Australian Open.
Kirilenko matched Hingis well, making frequent and effective use of the drop-shot.
The 19-year-old Russian was able to take advantage of her opponent's weak serve, which still appears to be Hingis' greatest vulnerability.
Kirilenko had plenty of chances to take the first set. She broke to lead 5-4 and was 40-0 up on Hingis's serve after the Swiss had levelled at 5-5. Hingis needed five points to close out the set at 6-5.
In the second set, Kirilenko served to level the match at 5-4 and 6-5 but Hingis dug deep and surrendered just one point in the tiebreak.
The conditions were slow, with rain halting the match early in the second set and falling lightly towards the end of it.
Because of the rain delay, Daniela Hantuchova was unable to play her first match since parting with coach Nigel Sears, and will tackle Anna Smashnova on Tuesday.
