Isn't Marq a new addition? I believe you acquired him just a few days ago. If so, don't worry because his behavior is absolutely normal.
When I first brought Giselle home, she refused to eat her breakfast for three days. On top of that, she had explosive Big D so I force-fed her handfuls of rice and chicken and Pepto Bismol. It was completely frustrating because I would stuff rice into her mouth and she'd spit it right back out. And, mind you, this dog was supposed to eat four cups of Nutro (that's what her foster mom was feeding her, but I switched to EVO/raw) AND she was at racing weight. Believe me, it's absolutely normal for a new addition to forego multiple meals. They'll nibble here and there, but they generally don't start wolfing down their meal until they've become acclimated to the new enviornment, which could take weeks. Giselle is a P I G, but I didn't find that out until it was her second month in. Or, perhaps, I created a pig
That seems a likely answer as well.
As for suggestions to eat, just be patient. He'll come around soon enough. I agree with the above posters and you should certainly wet down his food since there's been speculation that it makes the food more nutritious and appetizing. Additionally, you can add healthy "people food" like steamed veggies, steamed/plain boiled chicken, beef, lean hamburger meat, turkey, etc. Plus, since you're going to be using him in the ring, I would highly suggest adding "human food" and supplements because that will boost his coat and muscle condition. Raw/lightly steamed eggs, olive and Cod Liver oils, raw meat, and steamed veggies are popular add-ins as are natural yogurt and even the occasional slice of cheese. Good Luck with him!