Lyn Jones refused to write off his side's chances of reaching the knock-out phase of the Heineken Cup after seeing the Ospreys twice lose a lead against Gloucester at Kingsholm.
In the end, the English side won the ferocious Anglo-Welsh derby in Pool 2 by 26-18, thus making it nine points out of a possible 10 in the opening two rounds and denying their arch-rivals a bonus point into the bargain.
It was a result that left Jones and his team deflated after they had scored two first-half tries and battled back to lead 18-16 in the second half.
"We had the game in the palm of our hand, but we lost control of it. We are bitterly disappointed," said Ospreys coach Jones.
"The players put in a huge effort and it is mystifying how we didn't win the game. I thought we were the better side, but full credit to Gloucester for taking their chances.
"The most important thing now is that we turn up for the rest of our Pool games. We have four matches left and we have to win them all - something we are capable of doing.
"I think we are still good enough to go through, but we certainly need to win all our remaining games. There is still an enormous amount that is good in our game, but it was the little things that hurt us."
Finals Edition: Listen to the best guide to the European Rugby Cup Finals weekend in Dublin, which sees Leinster Rugby take on Stade Francais Paris at the RDS on Friday night in the Amlin Challenge Cup Final and then ASM Clermont Auvergne tackle Toulon in an all-French affair at the Aviva Stadium on Saturday.