Drake -- Working Out is Working Out ... Shows Off New Physique

Drizzy Drake’s been on a fitness RAMPAGE … posing for shirtless pics in a Bieber-esque frenzy ever since he started dropping lbs for his new tour … and it looks like all the work is paying off.

Drake's trainer posted this latest installment on Instagram today … and he looks jacked with a noticeable four pack … and wearing an expression that says “even I’m surprised I look this good.”

No word on what inspired the new work out regimen ... but he's definitely starting to look more like Rihanna's type.