Well this is the heavyweight division. And Grant does have power...so anything is possible. Highly unlikely though.
Grant is a bit of mystery, he won his fights last few years, against bad opposition but still, his confidence should be high. He is not that old and this is probably his last chance to become relevant again. And we all know about his size. Actually odds on Adamek are not that bad, so yes Grant has a chance. If Berret could beat Tua...
A Grant win is extremely unlikely. I have a copy of Grant's 2008 decision win over Paul Marrinacio, and Grant really looks shot. Basically, the speed, reflexes, and body-control (athleticism) are gone. Grant beat Marrinacio easily enough, but he does not look good. All Grant really has at this point is size, power, and strength. Adamek is leagues above Marrinacio in terms of speed, ability, and mobility. Adamek should avoid Grant's ponderous punches easily, and score a later round stoppage.
They are different kinds of fighters. Guinn beat Grant with power; he basically punched the ponderous, wide open Grant into kayo defeat. Adamek is less of a puncher than Guinn, but far more mobile and skilled. Overall, Adamek is better than Guinn ever was. I look for Adamek to stay on his motorbike for the first five or six rounds, deftly outboxing Grant and playing it safe. After that, Adamek's counterpunches will hurt a tiring, sluggish Grant more and more, and Adamek will turn up the steam. Stoppage probably comes somewhere around the ninth or tenth round. Grant's only chance is if Adamek does something stupid or absent minded, and runs into a powerful left hook. I doubt Adamek lets that happen, though. He seems pretty smart.
When we're talking about really big, powerful heavyweights, even the best of chins are vulnerable. Grant can still knockout anyone he hits. His problem is that his punches are slow and telegraphed. The word on Grant is that he's really deteriorated with age.