Potty Training Day 2

Not as successful as Day 1 and would love some suggestions. He does great when he's not wearing anything on the bottom half. When he's wearing underwear he pee in them right after peeing on the potty. He'll even play in the puddle he made, I have him clean it up though. Is he not ready for underwear or do we just need to get some that he really cares about and doesn't want to to get wet? Shortly after taking these pictures he peed and was fine walking around and playing in a wet shirt and underwear. Overall, I'd say he's doing great 2 accidents in underwear and 1 accident on the floor.