I'm not sure if this is your situation, but I'll offer this anyway.
Sometimes when kids don't feel incharge enough of themselves they resist authority. I think it is better to not get into a power struggle about these situations.
You might ask later, I notice you did this and was wondering about it. Then see what he says. You could also use a third person approach that kids will listen to more easily sometimes. Ex. Say sometimes when kids play baseball sometimes they don't want to listen to their coach. I wonder why?
Also giving kids more choices and being more in charge can help. My son prefers to do his morning chores in his order instead of mine. My kids prefer to pick out their snack for school to put in their school bag. Lots of little things can add up.
Also avoid telling kids what to do too much helps. This is hard for me but the more they can think for themselves the better. Parenting books give lots of tips on ways to talk to kids for better coroporation.
I hope some of this helps.
