Maria Sharapova hailed rival Justine Henin-Hardenne as a worthy world number one after losing to the Belgian in the semi-finals of the WTA Championships.
Sharapova won her second Grand Slam title at this year's US Open
Sharapova needed to beat Henin-Hardenne in their semi-final and go on to win the final to become number one herself.
"Not to finish number one is not so disappointing, I'm disappointed because I lost a match, that's all," she said.
"Justine deserves it, she was very consistent all the year round, in the final of all the Grand Slams."
Sharapova went into the match on the back of 19 straight wins, including victory over Henin-Hardenne in the final of the US Open in September.
But she was out of sorts from the start in their semi-final, going eventually down 6-2 7-6 (7-5).
"I didn't feel like myself, I had problems concentrating," said the Russian. "I tried to find a way to get back into the game. It was better towards the end.
"But there are days you're not at your best. Obviously today was one of them. There was a bit of fatigue, but it's not the key answer to the loss."
And the 19-year-old remained pleased with her efforts in 2006.
"I've had an amazing year, a very successful year, and I'll finish the highest I have in my career," said Sharapova.
"You always think about what went wrong and what could have gone better, but I'm happy with the way I played and just look forward to what I can improve for next year."