LOS ANGELES (AP):

Robert Plant and Alison Krauss' unorthodox partnership yielded rich rewards on Grammy night, as the pair nabbed five awards for their haunting Raising Sand, including record and album of the year honours.

But their sweep was overshadowed before the show even began when police announced that Chris Brown, himself a double nominee and scheduled performer, was being investigated for allegedly assaulting an unidentified woman the night before. Brown turned himself in to authorities and was briefly held before posting $50,000 bail Sunday night, jail records showed.

Brown and longtime girlfriend Rihanna, also nominated, were both slated to perform in different slots of the show, but separately dropped out at the last minute. The victim of Brown's alleged assault was not identified, and it was not immediately clear whether Rihanna's absence was related to Brown's.

Criminal threat

Police booked the 19-year-old R&B singer and dancer on suspicion of making a criminal threat, a felony. Police did not explain how their initial report of an injury assault related to the charge, but it will ultimately be up to the district attorney's office to decide what charges, if any, should be brought against Brown.

Back at the Staples Center, Lil' Wayne entered the evening with the most nominations and went home with four, including rap album of the year.

The pairing of the former Led Zeppelin rocker and Krauss, a bluegrass queen, may have seemed downright weird on paper, but the T Bone Burnett-produced album was universally acclaimed and highlighted Krauss' unique mastery of different musical styles. Subdued but emotionally stirring, Raising Sand was an artistic triumph for both artistes and perhaps demonstrated why Krauss is the most decorated female artist in Grammy history with 26.

Plant and Krauss had already won a Grammy last year for Gone Gone Gone (Done Moved On) from Raising Sand, bringing the record's haul to six. The single was released in time for Grammy contention that year, while the CD was not.

Emotional moments

Jennifer Hudson provided the night's most emotional moments onstage. The Oscar winner took her first Grammy award for best R&B album for her self-titled debut.

Hudson, 27, made no direct reference to the October killings of her mother, brother and nephew that kept her in seclusion until just this month. But, while fighting back tears, she made it clear that her family was foremost on her mind.

"I first would like to thank God who has brought me through. I would like to thank my family in heaven and those who are with me today.

Hudson later performed You Pulled Me Through, a dramatic song about overcoming deep despair.

The Grammy telecast was filled with eye-popping and eyebrow-raising performances, from Radiohead's collaboration with a college marching band to a televised black-and-white throwback performance from Jay-Z, T.I., Lil Wayne, Kanye West and a (very) pregnant M.I.A. on Swagga Like Us.

But not even these could patch up the gaping hole in the telecast caused by the absences of Brown and Rihanna. She was supposed to sing Live Your Life/Disturbia as the second performance of the night, he was later to sing Forever.

Coldplay won three, included song of the year for Viva La Vida.

Confused

"We've never had so many Grammys in our life," said lead singer Chris Martin, perhaps so excited he got confused (they had already won four over the years). "We feel so grateful to be here. I'm going to tear up."

British singer Adele was also teary, as she beat the Jonas Brothers, Lady Antebellum, Jazmine Sullivan and fellow Brit singer Duffy to nab best new artist. It was her second award of the evening.

She earlier won for best female pop vocal.