Jack Sock hasn't played since Aus Open where he retired against Capdeville, he probably lacks a bit match practice right now but if he's fully fit he'll do good against Matosevic today.
His Australian opponent is one of the players i find to be very overrated, he lacks a good serve and his backhand and forehand are decent at best. On top of that, his psyche is weak and he has a hard time keeping composure on court. I think Jack Sock will win this one if he is healthy, he might not be fully fit and he might even retire so this match is good to bet on at bookies that refund your stake if a player retires.
Odds are dropping on Sock, but 2,10 is still very good.
Jack Sock @ 2.10, 5/10 units