POP princess Britney Spears is getting married again.

EXCLUSIVE: Oops, Britney's doing it again 

The singer agreed to tie the knot with lover Kevin Federline after she crocked her knee and he went down on one.

The pair celebrated their engagement on Thursday evening with a lavish, hush-hush party for close family and friends.

A pal told the News of the World: "Britney is ecstatic. She has fallen head over heels for Kevin, but she wants to enjoy the moment in private. This time she really wants to do things properly."

Britney famously wed childhood sweetheart Jason Alexandar in a 5am Las Vegas ceremony in January.

The two friends had been on a two-day bender and tied the knot because it seemed "a funny idea at the time".

Hitched

Once their hangovers, and the joke, had worn off the marriage was anulled after only 55 HOURS.

Now, as Britney recovers from surgery on her knee—which gave way during a video shoot—she has had her second marriage proposal in six months.

With the last leg of her tour cancelled due to injury, the couple have had plenty of time to make plans and celebrate.

This week their closest pals and immediate family joined them at Britney's Santa Monica penthouse to toast their joy.

Our source in LA said: "It was when Britney was injured during her video shoot that they decided to get hitched.

"Since meeting Kevin, she's cut down on her drinking and has given up her partying ways to be with him.

"The cancelled tour is a blessing in disguise because it means they can now spend some quality time together."

Britney and Kevin, a dancer at LA dance agency Bloc, met through mutual friends a matter of months ago. We revealed their relationship back in April after they were spotted enjoying a romantic stroll on a Santa Monica beach.

Brit stripped down to a bikini and the smitten couple hugged and kissed.

Weeks later love-sick Britney flew Kevin 5,000 miles to be with her as she toured Europe.

Tattoos

And a fortnight ago they sealed their love with his and hers matching dice tattoos.

But their courtship has not been without problems after it emerged Kevin, 26, dumped his pregnant girlfriend to be with Britney, whose single Everytime is expected to top the charts today.