Murray needs to fight a very patient fight in this. I think the only thing he can do is keep a very, very tight defence and not give Martinez any real openings. The speed differential is a chasm the size of Antarctica, so he can't afford to be too ambitious with his output early on. I think he just needs to keep mental pressure on Sergio and hope for a slight decline in Sergio physically, which there have been a few signs of. He needs to play on the fact Sergio is at home for the first time in a while and will be under pressure to perform, and not really give him any opportunities to look good. If he can keep a mental pressure on him, stalk him around the ring, keep his punching straight and sharp, thats his only real chance. It's not too dissimilar to what Barker did, but Darren is a little fragile and more open defensively, Murray is much bigger so that will give him some hope.
I don't see why they don't double-bill this with Khan vs Matthysse, with the winner getting to keep the Falklands. With a war if it ends 1-1.