I believe it was season 5 or 6 of the Clone Wars when Savage and Maul fought against Palpatine, and i recently finished watching season 6 and I was thinking about how Maul felt this was going to turn out at the beggining of the fight. Also, his facial expression shows a smug or a face of overconfidence. I think one of the reasons he could be this way is because he had Savage on his side and a 2v1 would be hard for his master to deal with. I see this happen alot when maul fights someone, he thinks to highly of his abilities and ends up losing quite a majority of the time.