The boy also told Mays' attorney, Brian Duncan, that he hadn't seen the girl drinking and had not witnessed Mays involved in any sexual contact with the girl.
The trial, which is likely to stretch into the weekend, is moving quickly to accommodate the schedule of visiting Judge Thomas Lipps, who is presiding over the trial without a jury. A verdict is expected by Sunday.
The case has cast an unwelcome spotlight on Steubenville, a small, down-on-its-luck town along the banks of the Ohio River.
Critics have accused community leaders of trying to paper over rampant misconduct by players of the highly regarded Steubenville High School football team and have suggested that other students took part in the assaults or failed to do enough stop them.
The case has attracted the attention of bloggers and even the loosely organized hacking group Anonymous, which have questioned everything from the behavior of the football team to the integrity of the investigation.