If I heard that and I already bet for the heavy favorite, I would bet the same amount for the underdog. So that I will not lose a lot of money in that match. But if the heavy favorite win the game I will regret that I didn't trust my instinct in betting.
Nice counter if you have heard someone doing this. But this has never happened to me, I've heard about this but it's offshore and AFAIK there's someone that even posted here before with a basketball league somewhere on US but it's not NBA. I can't remember those information that he has given but it's clear that it's a fixed match base on what he said. And coming from someone who you don't even know? a total stranger will tell you about a fix match? kind of difficult to believe but if the organizers find it out, the athletes would be fined heavily.