Celtic's opener arrived in the 14th minute from the boot of Samaras after the former Man City striker picked up a long ball from Landry N'Guemo and twisted around the Motherwell defence to fire in a superb shot from 12 yards out into the top corner of the net.
An off the ball incident led to N'Zogbia confronting Wilshere before leaning his head into the Englishman and giving referee Lee Probert no choice but to show the red card.
Minutes later Martins took a pass from substitute Charles N'Zogbia before smashing the ball spectacularly past Kirkland from 15 yards as St James' Park erupted in what looked to be the defining moment of the match.