Fifth seed Nadia Petrova battled past Katarzyna Piter of Poland to reach the second round of the J&S Cup in Warsaw.
The 24-year-old Russian, who won three clay-court titles last season before injury saw her miss the French Open and Wimbledon, won 6-3 7-5.
"I was playing against two opponents," said world number nine Petrova. "One was on the other side of the net and one was on the same side as I was.
"I really had a difficult time because last week I didn't do much practising."
She added: "The previous week I played Fed Cup and that was indoors so it was completely different conditions."
Sixth seed Anna Chakvetadze also had to fight hard to book a spot in the second round.
The Russian overcame an inconsistent performance to beat American Jill Craybas 7-6 (8-6) 7-5.
But eighth seed Katarina Srebotnik was a first-round casualty, going down 6-3 4-6 6-1 to Alona Bondarenko of the Ukraine.
Defending champion Kim Clijsters, playing her only clay court tournament of her farewell season, is seeded second behind fellow Belgian Justine Henin.
Three-time runner-up Svetlana Kuznetsova of Russia is seeded three while 2004 champion Venus Williams is also playing but is unseeded.