SINGAPORE (AP) _ Americans Jim Courier and Jonathan Stark and Swedes Thomas Johansson and Magnus Gustafsson won their matches Thursday and advanced to the quarterfinals of the Heineken Open.

Courier, the No. 3 seed, had a tough fight from Michael Tebbutt of Australia bfeore winning in a tiebreaker, 6-4, 7-6 (7-2).

Stark, the defending champion,

used his big serve to defeat Jiri Novak of the Czech Republic 6-3, 3-6, 6-3. Novak made some great passing shots, but couldn't compete with Stark's dominant serve.

On Friday, Stark faces No. 7 seed Gustafsson, who beat Germany's Martin Sinner 6-7 (4-7), 6-4, 3-6.

Courier meets No. 5 seed Johansson, who handily knocked out South African Marcus Ondruska 6-4, 6-4.

The other quarterfinalists are No. 2 seed Marcelo Rios of Chile, No. 6 Martin Damm of the Czech Republic, No. 8 Nicolas Kiefer of Germany, and Sweden's Mikael Tillstrom.