Kris Commons fired the home side into the lead inside 15 seconds - but instead of a Hoops romp, Scott Vernon levelled with a minute of the first half remaining and Josh Magennis grabbed a double to set the Dons on the way to what would have been an unlikely victory.
However, Celtic showed the spirit of champions and Charlie Mulgrew reduced the deficit before Gary Hooper equalised with three minutes remaining, leaving the stage set for sub Samaras, who had replaced Beram Kayal, to hook in the winner with seconds left.
Billy McKay's controversial penalty secured Inverness a 2-1 home win against Highland rivals Ross County, lifting them above the Staggies into third place in the table.
The Northern Ireland striker's 24th goal of the campaign ended County's 11-game unbeaten run and has all-but ensured Inverness will have their first ever top-six SPL finish.
McKay netted the winner in the 59th minute after referee Iain Brines pointed to the spot when Charlie Taylor went down, but there were strong suggestions the full-back was making a meal of it.
It came after Andrew Shinnie's close-range opener in five minutes for Caley Thistle was cancelled out by a magnificent 30-yard strike from County's Paul Lawson.
The defeat leaves County fourth, two points behind Inverness.