Li Na, the first Chinese player to win a Grand Slam singles title, added another famous first to her collection when she reached the semi-finals of the WTA Championships with a 6-2, 6-1 rout of an ailing Victoria Azarenka on Friday.
It was the first time Li had qualified from the group stage of the tour's flagship tournament, and there was rarely any doubt that she would do so with a success which avenged her narrow defeat to the Belarusian at the Australian Open final in January.
The first thing I thought after the first set is that she (Azarenka) must retire. If I was feeling very bad I would have retired
Azarenka suffered a lower back injury in the sixth game and required three lots of treatment and significantly impaired her movement.
However, Li had already been looking the sharper and more potent attacker, and had become the favourite to deliver her third win in three encounters and finish top of her group.
"I thought after the first set she would retire," Li said of the injured Azarenka.
"It was tough for me to focus all the time. But you never know what will happen.
"The first thing I thought after the first set is that she must retire. If I was feeling very bad I would have retired. If you keep playing you can make an injury worse.
"But when I saw what happened I said to myself 'okay focus, and run for every shot'."
The result also ensured that Azarenka was eliminated and that Jelena Jankovic, the former world number one from Serbia, qualifies from the White Group in second place.
Jankovic will face Serena Williams in Saturday's semi-finals.