On Thursday, Celtic crumbled to a miserable defeat that denies them a place in the group phase of the Europa League.
The loss represents a massive psychological blow to Celtic's pride, and their finances, and it leaves the club's startup manager Neil Lennon under enormous pressure.
The team went into Thursday night's second leg with a 2-0 lead, still expecting to advance to the lucrative group stages. But that 2-0 advantage was quickly wiped out in a horrendous seven-minute spell which saw Ricky van Wolfswinkel net twice from the penalty spot before completing his hat-trick early in the second half.
Prior to the match there had been heavy rainfall all day and the slippery surface was causing problems for both sides, but Utrecht still managed to make an impressive start to the game.
To their shock Celtic found themselves trailing with just 11 minutes gone when the Spanish referee Carlos Velasco Carballo ruled that Michael Silberbauer was fouled in the box by Hooiveld. Van Wolfswinkel ably converted from the spot despite Zaluska getting a hand to the effort.
The Hoops' advantage from the first leg was gone completely seven minutes later when the referee pointed to the spot again, this time for Zaluska's challenge on Mertens. Again, van Wolfswinkel stepped up for the penalty and this time knocked low into the corner.
By this stage Celtic appeared shell-shocked by their dreadful start but had a chance to haul themselves back into the match when Efrain Juarez picked out Marc-Antoine Fortune. But his effort from just outside the box was poor and dipped well over the crossbar.
Celtic manager Neil Lennon addmited he was dissapointed: 'We had a decent advantage and we only needed to score one goal. But it's the overall performance, we were second best in just about every area really.'
'The first penalty was soft and for the second we shot ourselves in the foot. We've gone one down and just need to weather it and we get one goal and win the game. But we never gave ourselves a chance.'
'Refereeing decisions? I'm not going to go on about the referee because that would take away from a poor display. I would just be making an excuse, but two penalties is really poor from us.'
He added: 'I hope they're not a happy dressing room. Right throughout the middle of the team we were poor. We said, 'look you might have to weather a storm for 15 minutes.' But we keep shooting ourselves in the foot.'
Ireland Travel Tips
Is this Ireland's most haunted house? (VIDEO)