Um, the one where he is lying on his back, panting? I'm pretty sure it's the Ood episode from season 4 (with Donna) I'm blanking on the name but they go to a snowy planet and find the Ood being enslavedand help free them, and there's a ginat ood brain thing... uh yeah, does that help? It's the scene in the warehouse where Ten is chased by a giant claw thing