Katara's senses were not asleep, especially not when it came to battle. she saw what the boy was doing, but decided not to mention it. He was a strong fighter all his own, but she'd had stamina she learned to keep reserved if she needed it. Sometimes fighting like this could mean life or death, and if she jumped into things too rapidly, it could be fatal.

When he went for the strike, she didn't need to be on the offense, which was fine, as defense was more her specialty anyway. She used her arm to sweep the strike aside, putting one foot back to steady, and using her arm to muscle him to her and then to the ground.