Steffi Graf, overcoming her toughest test of the tournament, beat fifth-seeded Helena Sukova of Czechoslovakia 6-4, 6-4 at the Australian Open Saturday to capture her fifth straight Grand Slam title.

Sukova jumped to a 4-3 lead in the opening set before Graf took control with her fierce forehand and won the next seven games. Sukova mounted another challenge in the second set, saving two match points to close within 4-5, but Graf held serve on a forehand pass to win the match.The 71-minute contest, played in 100-degree heat at the National Tennis Center, was Graf's longest of the tournament. The 19-year-old West German also lost more games than in any of her previous matches during the two-week event.

Graf is only the fourth woman to win five consecutive Grand Slam titles. Martina Navratilova, Margaret Court and Maureen Connolly each won six Grand Slam events in a row.

Graf, playing in her eighth consecutive Grand Slam final, did not drop a set in the tournament for the second straight year. The world's top-ranked player has lost only two sets in Grand Slam competition since beginning her five-title string at last year's Australian Open.

Graf earned $135,000 for winning the championship. Sukova, who was also runner-up at the 1984 Australian Open, received $67,500.

It was Graf's sixth Grand Slam title overall. She also won the 1987 French Open.

On Friday, Ivan Lendl and Miloslav Mecir conquered a sizzling sun and underdog opponents to set up an all-Czech men's final.

Lendl outdueled 11th-seeded Thomas Muster of Austria 6-2, 6-4, 5-7, 7-5 in a baseline battle, while Mecir dismantled unseeded Swede Jan Gunnarsson 7-5, 6-2, 6-2 with quickness and cunning groundstrokes.

The victories set up a rematch of the 1986 U.S. Open final, which Lendl won in straight sets. Lendl has won three U.S. Opens and three French Opens, but still is seeking his first Australian Open title.

"Winning this tournament is important to me," said Lendl, who will regain the No. 1 ranking if he wins Sunday's match. "If someone wants to beat me, he's going to have to take it. I'm not going to give it away."

Lendl has a 4-1 record against Mecir, a gold medalist at the Seoul Olympics.