February 9, 2009 - LOS ANGELES – 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 honors. 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 wasn't identified, and it wasn't immediately clear whether Rihanna's absence was related to Brown's.

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 with eight, 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 artists, and perhaps demonstrated why Krauss is the most decorated female artist in Grammy history with 26.

"We ostensibly come from such different places on the musical map. There are radical differences in the ways we've gone about enjoying our lives as musicians," Plant said backstage after the show. "Alison has shown me so much of the America I've never been exposed to. There's so many songs in the air. America needs to know what it's songs are all about."

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.

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, with the lyrics: "When I was drowning, when I was so confused, you, you pulled me through." As she sang the last note, she looked directly into the camera and dissolved into tears once again.

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."

And each was nominated in the pop collaboration with vocals category, Brown for "No Air" with "American Idol" champion Jordin Sparks; and Rihanna for "If I Never See Your Face Again" with Maroon 5. Brown was also nominated for male R&B vocal performance for "Take You Down."

Neither won a Grammy on Sunday, and the Recording Academy found able replacements for their performance slots in Justin Timberlake, Al Green, Boyz II Men and Keith Urban as they all sang Green's classic hit, "Let's Stay Together." No mention was made on the broadcast about the switch.

At about 3:30 Pacific time, just as the crowd was filing into the Staples Center, Los Angeles police released a report saying Brown was under investigation for an incident the night before. The report said he and a woman were driving in the ritzy neighborhood of Hancock Park when they began to argue around 12:30 a.m. Sunday. Brown stopped the car and both got out, whereupon the argument escalated, the report said. The woman, who had visible injuries when police arrived, identified Brown as her attacker, but he had left the scene, the report said.

Police said Brown walked into a station around 7 p.m. and was interviewed by detectives, and was released after posting bail before 9 p.m. A black SUV was later seen leaving the jail facility, but it wasn't immediately clear whether Brown was inside.

Around the same time, Lil Wayne won the first Grammys of his career for "Tha Carter III," which took the 26-year-old rap veteran to from rap to pop MVP. It wasn't entirely his fault for not sweeping all eight of his nominations: he was competing against himself in two categories in which he won.

Besides rap album, he won best rap solo performance for "A Milli," rap song for "Lollipop" and rap/sung collaboration for "Swagga Like Us."

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

"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.

"Thank you so much. I'm going to cry. I want to thank my manager, my mom, she's in London. And Duffy I love you. I think you're amazing. Jonas Brothers, I love you as well," she said, delivering that last bit with a devilish look, eliciting laughter.

It was Adele's second award; she earlier won for best female pop vocal.