Britney Spears Says in New Book She Had Rough Sex with Colin Farrell

Britney Spears is dishing on what she claims was a two-week hot romance she had with Colin Farrell years ago -- comparing their quickie affair to a "street fight."

The pop star wrote about her fling with Colin in her new memoir, "The Woman In Me," which is set to be released next Tuesday.

In a new excerpt from the book, obtained by TIME, Britney says she first met Colin through a club promoter on the set of his 2003 film "S.W.A.T."

Britney says the sparks flew immediately and the stars wound up having a lot of rough sex, describing it as a "two-week brawl."

She added that "brawl is the only word for it -- we were all over each other, grappling so passionately it was like we were in a street fight."

Britney also says her bedroom romp with the Oscar-nominated actor came after then-boyfriend Justin Timberlake broke up with her in 2002.

She admits she wasn't "over Justin" when she appeared alongside Colin at the opening of his 2003 movie, "The Recruit." She says she was vulnerable after the split with Justin, but tried to convince herself "it was not a big deal" and she was "just having fun" with Colin.

At the premiere, Colin told the media he was "not dating" Britney, but referred to her as "a sweet, sweet girl."

That same year, Britney told "W Magazine" she kissed Colin and thought he was the "cutest, hottest thing in the world," but their relationship was "nothing serious."

In her memoir, Britney doesn't get into what led to the end of her sexual liaison with Colin, but she offers this instead ... "For a brief moment in time, I did think there could be something there. The disappointments in my romantic life were just one part of how isolated I became. I felt so awkward all the time."

Several excerpts from Britney's book have already leaked to the media. This week, TMZ broke the story about her tell-all bombshell  ... Britney and Justin made the gut-wrenching decision to abort their unborn child while they were dating in the early 2000s.