Justine Henin-Hardenne will end the year as world number one after reaching the semi-finals of the WTA Tour Championships.
She reached the semi after beating Jennifer Capriati 6-2 6-1.
Anastasia Myskina kept alive her hopes of reaching the semis with a 6-4 6-3 round-robin victory over Ai Sugiyama.
She must now beat Capriati in her final group match to reach the last four.
Defending champion Kim Clijsters completed her round-robin matches with her third win, beating Amelie Mauresmo 3-6 6-4 6-4.
Clijsters has already qualified for the semis while Mauresmo's hopes depend on the result between Chanda Rubin and Elena Dementieva.