That heavily stylized image on El Potro's Sin Fronteras is no joke. After all, this is an artist who has often tried on -- and pulled off -- various style experiments. Here, he puts on his crooner hat, covering beloved songs drawn from across the spectrum but gussied up in rich regional Mexican. And like a good crooner, El Potro has the pipes and the charisma to make each one his own. So "Bachata Rosa," which Juan Luis Guerra coated in sweet romanticism, becomes salty and earthy. And "Yo No Se Mañana" retains some of Luis Enrique's sentimentalism, but cuts it with a weary mournfulness.