After storming into a 3-0 lead by the 50th minute, Chelsea conceded two penalty kicks that Wayne Rooney converted before Hernandez completed the comeback.
United ended the weekend two points behind Manchester City, which beat Fulham 3-0 on Saturday.
"It's two points lost," Rooney said. "We understand that. But after being 3-0 down -- the City players at home must have liked that -- we enjoyed the way we fought back."
The draw left Chelsea clinging to the league's fourth Champions League qualification spot, one point ahead of Newcastle.
Copyright 2012 by The Associated Press
