Den Bosch - Top-seeded Kim Clijsters beat Monica Niculescu 7-5, 7-5 on Monday in the first round of the UNICEF Open, a grass-court warmup for Wimbledon.
In the men's tournament, top-seeded Nicolas Amalgro lost to Michael Berrer of Germany 3-6, 7-6 (5), 6-4.
After leading 4-2, Clijsters lost three straight games before winning three in a row to finish the set.
In the second, Clijsters broke Niculescu in the sixth game, but the Romanian broke right back and then both held serve until Niculescu double-faulted to end the match.
"It always takes a little getting used to," Clijsters said of her first match on grass this year. "It was important to stay focused on every point."
Second-seeded Svetlana Kuznetsova of Russia also advanced, beating Arantxa Rus of the Netherlands 6-2, 6-4.
Marcos Baghdatis also reached the second round. The second-seeded Cypriot defeated Arnaud Clement of France 7-6 (4), 6-3.
"I started a little nervous, so I'm happy I won," Baghdatis said. "It was a great victory today."
Nicolas Mahut of France advanced by eliminating sixth-seeded Adrian Mannarino 7-6 (2), 6-3.
Results from the second day of the ATP/WTA UNICEF Open:Marcos Baghdatis (CYP) bt Arnaud Clement (FRA) 7-6 (7/4), 6-3
Kim Clijsters (BEL x1) bt Monica Niculescu (ROM) 7-5, 7-5
Romina Oprandi (ITA) bt Akgul Amanmuradova (UZB) 6-4, 6-3
Flavia Pennetta (ITA x4) bt Alona Bondarenko (UKR) 6-4, 6-4
Svetlana Kuznetsova (RUS x2) bt Arantxa Rus (NED) 6-2, 6-4
Yanina Wickmayer (BEL x3) bt Alberta Brianti (ITA) 6-4, 6-0
Kimiko Date Krumm (JPN) bt Maria Kirilenko (RUS x6) 7-6 (7/5), 6-2
Alexandra Dulgheru (ROM) bt Alison Van Uytvanck (BEL) 7-5, 7-6 (9/7)
Arantxa Parra (ESP) bt Laura Robson (GBR) 7-5, 6-3
Kristina Barrois (GER) bt Barbora Zahlavova Strycova (CZE) 6-3, 6-2
Denis Gremelmayr (GER) bt Ludovic Walter (FRA) 6-3, 7-6 (7/5)
Michael Berrer (GER) bt Nicolas Almagro (ESP x1) 3-6, 7-6 (7/5), 6-4
Nicolas Mahut (FRA) bt Adrian Mannarino (FRA x6) 7-6 (7/2), 6-3
Dmitry Tursunov (RUS) bt Robert Kendrick (USA) 6-2, 7-6 (7/3)
Filippo Volandri (ITA) bt Ricardo Mello (BRA) 6-4, 7-6 (7/5)
Teimuraz Gabashvili (RUS) bt Konstantin Kravchuk (RUS) 6-4, 1-6, 6-4