Britney Spears' ticket sales are "down considerably".

The "Womanizer" singer is concerned her comeback tour, "The Circus Starring Britney Spears" will flop after a large number of concert tickets remain unsold for the opening show in New Orleans March 3.

A source said: "Group sales are down considerably, and then you've got individual tickets that cost as much as $500 apiece. That's a lot of money to spend on an artist who isn't a sure bet right now."

The source added: "She's worked really, really hard to make this good. Granted, there've been some hiccups along the way, but she's going to put on a good show. I just hope there are people there to see it. This is really her last chance."

Meanwhile, it has been reported the Pussycat Dolls - who are due to support Britney on the tour - have been caught up in a row over costs.

The girls apparently want to take their male back-up dancers on the road but have been told it will be too expensive.

In a leaked email between their record label head Jimmy Iovine and the band, he said: "We can't afford it. I'm sorry its hard enough right now with the album not selling that's why we did jai ho and re-releasing the album. And we want to be able to keep the whole thing going at this level its not a choice its a reality."

(China Daily/Agencies March 4, 2009)