Now Weir wants the Glasgow giants to hit back from the disappointment.
“It'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."