Playing in his first game on loan from Middlesbrough, Egyptian striker Mido scored on a penalty kick in the 83rd minute to give Wigan a tie at the JJB Stadium.
The outcome left Liverpool manager Rafael Benitez fuming.
"In the second half," he said, "I was not happy with a lot of things."
Chelsea is tied with Liverpool after its 2-0 win over Middlesbrough on a pair of goals by Salomon Kalou.
Aston Villa, a 1-0 winner over Portsmouth on Tuesday, is fourth, a point behind Liverpool and Chelsea.
A last-gasp equalizer from Robin van Persie gave Arsenal a 1-1 tie at Everton that left the Gunners in fifth place, eight points behind Manchester United. Everton would have leapfrogged Arsenal with a win. Howard had saved a strong header from van Persie earlier in the second half.