Liverpool have been pressing Stoke hard for much of the first half but the Potters were woken up by the England striker's opening goal of the Premier League season.
Luis Suarez made an appearance on the Anfield pitch before kickoff, but failed to make Brendan Rodgers' final squad.
“We’re Stoke City! We play on the floor!” was the chant from away fans throughout the game as the Potters impressed with their new style of play.
However, it was Mignolet on his Reds debut who was the decisive keeper after he saved Jonathan Walters' 88th minute penalty. Dan Agger was judged to have handled across, but Mignolet saved his blushes by turning aside Scouser Walters' spotkick.