This wasn’t as much the pupil defeating the mentor, but the mentor’s son defeating the pupil. Or, if you’re scoring (which the Rangers rarely do if Rick Nash isn’t on the ice), it was Ottawa goaltender Robin Lehner, whose father Michael was Henrik Lundqvist’s goaltending instructor in Sweden, coming out on top of The King and the Blueshirts 3-2 last night at the Garden. “It was pretty cool for me to play against Robin; I’ve known him since he was 12 years old,” Lundqvist said after the match in which the Rangers wilted over the final 12 minutes and thus failed to extend their winning streak to five games. “I’m sure it was special for him, too.” Lehner, who at 21 is 10 years Lundqvist’s junior, said Thursday had been a nerve-wracking day, as he anticipated facing The King. The Ottawa goaltender, who made a spectacular, lunging point-blank save on Derek Stepan at 6:43 of the third that not only preserved a 2-2 tie but ignited a Senators’ surge that lasted the rest of the way, reported that his dad had found a way to watch the game while on vacation in Sweden, even as the match commenced at 1 a.m. his time.