Ricky Martin's last No. 1 on Billboard's Hot Latin Songs chart was the sumptuous "Tu Recuerdo," a duet with Chambao frontwoman La Mari from his 2006 "Unplugged" album. For his new single, the Latin superstar offers another intimate duet with a Spanish singer -this time Natalia Jimenez of La Quinta Estacion-and the collaboration is just as potent. Over laissez-faire, reggae-inspired guitar and percussion, Martin and Jimenez trade playful verses about a deeply satisfying relationship, achieving a dynamic similar to that of Jason Mraz and Colbie Caillat on "Lucky." It's tough to resist connecting Martin's opening lines ("I finally feel happy/Sadness is not for me") with his personal triumphs of the past year, but this subtext makes "Lo Mejor de Mi Vida" feel all the more like a genuine expression of delight.