Belgium's Justine Henin-Hardenne reached the semi-finals of the WTA Tour Championships - and ensured she ended the year as world number one - with a 6-2 6-1 win over Jennifer Capriati.
Henin-Hardenne, who won the French Open and US Open titles, had needed medical treatment for her racing heart and the lingering effects of a sinus infection before the match.
But she looked in great shape as she dominated Capriati, who was hindered by a hip muscle strain.
Henin-Hardenne didn't face a break point in the 59-minute match but broke Capriati twice in each set.
"It is just amazing, because the season has been great," said Henin-Hardenne. "I won two Grand Slams. I did everything almost perfect.
"So it is great to finish the season number one. I can't believe it right now, I don't realise it yet."
Clijsters W3 L0
Mauresmo W1 L2
Rubin W1 L1
Dementieva W0 L2
Henin-H W2 L0
Myskina W1 L1
Capriati W1 L1
Sugiyama W0 L2
Anastasia Myskina kept alive her hopes of reaching the semi-finals of the WTA Tour Championships with a 6-4 6-3 round-robin victory over Japan's Ai Sugiyama.
The Russian recovered from two early service breaks to win in just over an hour.
She must now beat Capriati in her final Black Group match to reach the last four.
Myskina's win helped erase her heartbreaking 7-5 5-7 7-5 loss to Henin-Hardenne that had kept her on court until nearly midnight on Thursday and up crying long after that.
"I'm really proud of myself that I was able to recover," said Myskina.
"It was tough for me. I didn't sleep well. I was thinking 'How stupid can you be, to lose a set when you're up 5-0?'
"I was so mad at myself I was crying for a couple of hours."
Defending champion Kim Clijsters completed her round-robin matches with her third win, a 3-6 6-4 6-4 defeat of Amelie Mauresmo.
Clijsters had already qualified for the semis while the fate of Mauresmo hinges on Saturday's Red Group match between Chanda Rubin and Elena Dementieva.