DUBAI (AFP) — Serena Williams, the world number one, and Victoria Azarenka, the only unbeaten leading player on the women's tour this year, have been penalised for their late withdrawals from the Dubai Open.

Williams, who had a bad back and withdrew on Wednesday, has had US$50,000 forfeited from the WTA's bonus pool, and zero points imposed for one tournament on her world ranking calculation.

Azarenka, who had a bruised heel and withdrew on Monday, had US$100,000 forfeited from the WTA's bonus pool and zero points imposed for one tournament on her rankings calculation.

Azarenka's stronger punishment reflects the fact that hers was the second successive time she had pulled out from the Dubai Open after the entry deadline.

Tournament Director Salah Tahlak said: "I had a conference call with the WTA in Florida and they are taking action against Azarenka, relating to her second successive withdrawal. There is also action against Williams.

"The WTA apologised to me. It's unfortunate that it happened, but sometimes it is better that they (the players) are not pushed too hard. It can be better for the sport. When I saw Serena she looked really bad.

"It is very disappointing both for the tournament and for the fans, some of whom come from all over the world to be here. But both players have promised to come back here next year, so for me the matter is now closed."

The incidents are a setback for the WTA Roadmap's campaign to reduce the number of player withdrawals, something it appears to have done successfully over the past three years.

The situation was further complicated by the fact that Dubai Duty Free, the sponsors of the Dubai Open, are also sponsors of the WTA tour.

The forfeitures, however, seem of little financial consequence when the bonus pool total is as much as $4,900,000, and when these two players also earn many millions of dollars a year from prize money and sponsorships.

The zero points imposed is also unlikely to have much, if any, adverse effect on the ranking of either, when calculated alongside their many successes.

Williams, who took over from Azarenka as world number one on Monday, became sure of keeping the top spot at least until the start of April as soon as the Belarusian withdrew.