Earlier this month, Kanye West released a new track featuring music legend Paul McCartney. The move purportedly dumbfounded many of the rapper's fans, who took to social media to ask, in apparently exasperated fashion, who exactly this Paul McCartney person is. The reaction was not unlike the one the former Beatle received after appearing on the Grammys three years ago. Now, in what will inevitably result in another round of both genuine and sarcastic head-scratching, West and McCartney have teamed up with pop superstar Rihanna. It's been a merciful 26 months since the Barbadian singer's last album, Unapologetic, but it looks like she's gearing up for her comeback. Last night, RiRi tweeted "FIRST GLIMPSE AT MY NEW MUSIC!!!" (emphasis hers) with a link to her website announcing her new single, "FourFiveSeconds," a midtempo acoustic jam featuring McCartney on guitar and Rihanna and Kanye trading verses about a night of wilding. "The Loveeeeeee Song" singer has often thrived outside of her usual dance-pop pigeonhole, particularly on reggae-tinged tracks like "Man Down" and understated ballads like "Stay," but the stripped-down format of "FourFiveSeconds" only serves to highlight her vocal shortcomings. "I think I've had enough/Might get a little drunk," she sings, with a raw, off-kilter, Tuesday Night Music Club quality. But rather than charmingly rootsy, her voice is scratchy and strained; belting has never been Rihanna's forte, and it's as painful as it's ever been here.