THIS was the meeting of the immovable obstacle and the immovable obstacle and, inevitably it took a long time to resolve. The first game of the match between Li Na and Agnieszka Radwanska lasted 12 minutes, and already there were rueful knowing smiles on the faces of both players: they knew it would be like this.
The first set took more than an hour, longer than a typical Serena Williams match. The match took more than 100 minutes, long enough generally for Williams to play, win, shower, get a rub-down and be at the first shop.
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Li Na stunned Agnieszka Radwanska in straight sets, advancing to a Semi-Final clash with Maria Sharapova, who beat Ekaterina Makarova.
Without further ado, it should be reported that Li won in straight sets. This restored the fine balance between them. Each has played 14 matches this year, and lost only once, to the other. Radwanska already had won titles in Auckland and Sydney. Li won a tournament in China and, with luck, could add the Australian Open.
When beaten by Radwanska in a semi-final in Sydney she said she was weary from jetlag and from having to play every day. The format of a major, with a day off between matches suited her. Li said she had made a point of not looking at her draw here, so as to keep an uncluttered mind. Now it is staring at her, and it is a semi-final.
In Li versus Radwanska, the serve was like the ''how are you?'' that follows ''hello'', an unthinking formality, a tic. Only one will be remembered. Li, with sunspots dancing in her eyes, served one ball on the full into the crowd at the other end of the court. Radwanska said she understood. Having played so many matches around noon here, she knew that the sun could be blinding. From another, this might have been read as a complaint: No.4 in the world, yet always on the undercard.
Ball introduced, Li and Radwanska locked horns, while the sparrows chirped. ''Always tough, always tight, long rallies, long game,'' Radwanska said, reflecting on their rivalry. But there are long rallies and long rallies. Neither of this pair ever hit a shot merely for the sake of it. Both were aware that neither was powerful enough to overwhelm the other, but neither was prepared to leave it at that. They crafted each stroke for a particular effect, searching for an opening, Radwanska sometimes by going on bended knee to drive down the line, a la Michael Slater.
''Against her, you have to focus on every shot,'' Li said. ''Not every point, every shot.'' Returning the compliment as she would a forehand, Radwanska said: ''She's a very consistent player. She's always playing on the same level. It's not up and down like the other girls. She's always solid.''
So well were they matched that they twice traded clips of the net, back-to-back. Otherwise, they exchanged mutual gestures of bemusement as one, then the other, undid a well-laid plan. Initially, that pattern was for Radwanska to wash off the pace at a judicious moment, causing Li to over-hit. Once Li found her range, she was the more threatening of the pair. But still it took her four extra shots to finish off Radwanska on set point, as if stamping on a cockroach that would not stop wriggling.
Radwanska won the first eight points of the second set. For Li, this was a crisis; suddenly, she felt leaden in the legs. ''I was feeling totally dying,'' she said. ''She's a tough player. I was feeling against a wall.'' Just as suddenly, the crisis passed. Li put this down to her decision after last year's Wimbledon to replace coach Jiang Shan - also her husband - with Carlos Rodriguez, formerly coach to Justine Henin.
One effect was to eliminate confusion about Jiang's place. The other was to introduce her to a killing off-season training regime. After three days, she said to her husband: ''He is crazy.''
Now, though, she had her reward. She came again, winning nine points in a row to assume control. Radwanska faded, and wondered later if this was accumulated fatigue. ''Definitely, I think I wasn't fast enough today,'' she said.