The Nigerian has impressed since joining Celtic over the summer from Israeli club Ashdod but he cost them two points on Sunday when a late own-goal handed Dundee United a 2-2 draw at Tannadice.
That mistake and the late heartbreak at the Nou Camp, when the SPL champions were denied a point by Jordi Alba's 94th minute winner, has left Ambrose determined to cut out the slackness ahead of the reverse Parkhead fixture.
"For me, after scoring the own goal, what went through my mind was that I let the team down and I let myself down too. I should have done better with the ball but I didn't," he said.
"But that is football, that is part of the game, and the important thing is how you move on and how you react to situations like that.
"It was my first own goal of my career and now I want to pay back the Celtic fans. Yes, it was very disappointing, but we have recovered and it is behind us now.
"We conceded two goals in two minutes, which is not good enough, and we have to take full responsibility for that and hope that these kind of mistakes never happen again.
"The last game was hell for us in the Nou Camp, because we fought until the last minute before Barcelona scored.
It's very worrying that we've lost our concentration so late in these matches.
"In the Nou Camp, it was the 94th minute and then at Tannadice it was two late goals in two minutes, so we need to sort that out.
"We've talked about it with the manager and we know what we need to do - and we will do it. At a time like this we need to be more focused and go to the last minute and keep our concentration until the very end. We need to put effort in to make sure this does not happen again."