Chris Brown accepts the award for best R&B album for "F.A.M.E." at the 54th annual Grammy Awards in Los Angeles, California, February 12, 2012.[Photo/Agencies]

R&B singer Chris Brown has earned a measure of musical redemption and forgiveness from ex-girlfriend Rihanna by collaborating on new music together, three years after Brown pleaded guilty to assaulting the pop star.

Brown, 22, and Rihanna, 24, were openly tweeting each other and promoting their collaboration on each others' singles over the weekend as the Barbadian "We Found Love" singer celebrated her 24th birthday.

"@chrisbrown Turn up the music remix #RihannaNavy #Teambreezy enjoy!!!" the birthday girl tweeted on Sunday with a link to her collaboration on Brown's single, "Turn Up the Music," before posting another tweet with a link to her duet with Brown on a remix of her single "Birthday Cake."

Rihanna provided vocals on a remix of Brown's new uptempo dance song "Turn Up The Music" while Brown lent his voice to Rihanna's sexually-charged song "Birthday Cake."

Their reconciliation, which has been the topic of much speculation in the media after the two were spotted together numerous times, comes after Brown made his official return to the Grammys on February 12 and won one award, prompting him to lash out at critics saying, "HATE ALL U WANT BECUZ I GOT A GRAMMY Now!" on his Twitter.

The singer almost derailed his career three years ago on the night before the Grammys, after he was arrested for beating up his then-girlfriend, Rihanna, and since then, Brown has been working to rehabilitate himself in the eyes of fans.

His musical reunion with Rihanna had social networks abuzz through the weekend and into Tuesday, as critics and fans were split on the newly released duets, with some making cynical puns, others calling it a publicity stunt and the rest embracing the new songs.

"#Rihanna and Chris Brown are recording a song together, I guess she was concerned about being a one hit wonder," said user @GreenRoomShow on Twitter, while another user, @ElsaBreezy, posted "I Respect Rihanna And Chris Brown For Collaborating Despite Knowing There Will Be A Lot Of Negativity From The Losers Who Are Stuck In 2009."

Brown's "Turn Up The Music" is currently at No. 8 on the iTunes singles chart, while Rihanna and Brown's duet on "Birthday Cake" is circulating the Internet after being offered as a free download by the singer over the weekend.