FRANKFURT, NOV. 15 -- Boris Becker and Ivan Lendl eased into the semifinals of the ATP World Championships with straight-set victories today.

Becker beat Thomas Muster, 7-5, 6-4. Lendl beat Andres Gomez, 6-4, 6-1.

Andre Agassi kept alive his chances of advancing by routing Emilio Sanchez of Spain, 6-0, 6-3, in 53 minutes to give him a 2-1 record in the round-robin portion of the eight-man tournament.

While Becker and Lendl were certain to advance from their group, the second semifinalist from Agassi's group won't be known until Friday's match between Stefan Edberg and Pete Sampras.

Edberg, the top-ranked player in the world and the defending champion, appeared certain to qualify after beating Agassi in three close sets late Wednesday. But ATP officials said the complicated tiebreaking system would favor Sampras if he beats Edberg and three players finish 2-1 in the group.

Edberg is 2-0 and Sampras is 1-1 but Sampras has a better percentage of sets won.

Becker and Muster exchanged some spectacular shots in a hard-fought first set.

The best moments were in the 11th game when Muster saved five break points. Becker then chased down Muster's forehand to the corner and Muster was wide on a volley at the net to lose the game.

Becker served out the set and took a 5-1 lead in the second as Muster's game became sloppy and Becker kept him pinned far behind the baseline.

Becker wasted four match points on Muster's serve in the seventh game. Muster held serve when Becker hit a backhand wide, then went on to break Becker at love in the next game.

Lendl had little trouble beating Gomez, who has struggled to find his form after winning the French Open this summer.

Notes: Agassi said he will join Becker and John McEnroe in snubbing the $6 million Grand Slam Cup scheduled Dec. 11-16 in Munich. The winner in the 16-man field will earn $2 million.

The Grand Slam Cup is being organized by the International Tennis Federation and the directors of the Grand Slam tournaments. . . .

The eight world tennis championship finalists will be committed to 10 tournaments instead of 11 next year, the Association of Tennis Professionals announced.

"The argument of the players has been that the commitment of 11 championship events is more demanding for a top-rate player than a 50th-ranked player," ATP chief executive Mark Miles told a news conference.

"The 50th-ranked player is often packing up to go home on Wednesday while the top-rate player is still there on Sunday."