Now Weir wants the Glasgow giants to hit back from the disappointment.
â€œIt's up to us, we've got to regroup and look at what we did wrong and we've got to get better at it," said Weir.
"We are disappointed and that's the over-riding feeling. We've got to pick ourselves up and start again.
"We lost the game, that's the bottom line. The game was very tight and I don't think there was a shot on goal from either side up until the first goal.
"Celtic got the first goal and that gave them something to hold on to and a bit of impetus. It turned out to be the turning point in the game."