Groundwork will be key here. If you can keep hold of him and not endanger yourself when he's excited and trying to get out into the pasture ASAP, walk him back out of the pasture and let him sit and calm down (this may take several minutes as he may be confused as to why you're walking out of the pasture when he knows he's about to be turned out). After a few minutes walk him back in as if you're going to turn him out, if he proceeds to get excited and attempt to run off before you get the halter off, walk him back out again. Just repeat this until it clicks that if he tries to get away, he won't be let loose. He'll realize soon enough that if he fights you he'll have to wait that much longer to go play with his buddies, and let's face it, no horse wants that!