Celtic's surprise defeat at Tynecastle left them eight points behind their arch rivals Rangers before next Sunday's win-or-bust showdown at Ibrox.
Martin O'Neill's men still have a game in hand and Stamp agrees with the manager's declaration that it would be dangerous to write them off just yet.
And the Englishman gave them further hope that there was a twist in the title race after vowing to inflict the same pain on Rangers at Tynecastle on May 17.
"You can never count Celtic out," insisted Stamp. "It's a funny game and Rangers still have to come here as well. We have shown that this is a difficult game for the Old Firm, but I would think that Rangers now look set to go on and win it. But I don't see why we can't do the same to Rangers here despite what has happened I still think Celtic are a better side than Rangers."
The former Middlesbrough midfielder hailed Hearts' performance as the best in his and manager Craig Levein's time at the Edinburgh club.
They showed great spirit which is what Celtic must produce in Portugal this week to come back from behind after Henrik Larsson had scored his 39th goal of the campaign.
Stamp equalised before Austin McCann's sensational injury-time strike sunk the champions and he believes they have now crashed through the mental barrier of beating the Old Firm.
"It is a fantastic result to beat Celtic and it is the best performance since I have been here and the best since the manager's been here," he enthused.
McCann's stunning winner his first for the club deserved to decide the game and could now earn him goal of the season.
Manager Craig Levein joked that he gave up hope of him ever scoring in a match and his team-mate believes it will be a few years before he hits one better.
"He has a fantastic left foot and he does it week in week out in training," revealed Stamp.
"It could be a really long time before he scores a better one." Celtic manager O'Neill was remaining defiant despite the massive setback but he concedes that the games are running out for his side.
He is clinging on to the hope that his side can beat Rangers next Sunday.