Portsmouth coach Kevin Bond admitted the exit of manager Harry Redknapp was a factor in the 3-0 defeat to Watford.
"It's a massive opportunity lost," said Redknapp's ex-assistant. "We won't make excuses but it's been a difficult time.
"We had the chance to get back on track what with the trophy and a Uefa Cup place at stake.
"Let's face it we had the best draw playing Watford and although we knew it would be tough we should have been favourites."
Bond revealed goalkeeper Jamie Ashdown had admitted responsibility for the
vital opening goal on 22 minutes.
He said: "Jamie held his hands up for that one and it's such a shame because he has been brilliant for us.
"We just didn't get going. We had plenty of possession but their goalkeeper was on hand to make some saves when we got something on target and the two goals
after the interval killed us.
"There is nothing we can do now, it's finished. I'm just looking ahead to the game against West Brom at the weekend."