Everton were left baffled as their hopes of a place in next season's Europa League came to an end following a 0-0 draw at Stoke on Saturday.
Needing a victory to maintain their challenge, it looked as though they would be granted that wish when Phil Jagielka found the net in the 72nd minute.
The defender's firm downward header from Mikel Arteta's corner was helped in by goalkeeper Asmir Begovic.
However to Everton's astonishment referee Howard Webb disallowed Jagielka's effort, apparently because Victor Anichebe was offside.
The decision left manager David Moyes baffled and remonstrating with the fourth official.
Moyes skipped the post-match press conference and his assistant Steve Round said: "We thought it was a perfectly good goal. We cannot quiet understand why it was disallowed. The officials made the decision and we have to respect that.
"He (Anichebe) is in an offside position but is he interfering, I don't know. We have taken a corner and it has been headed straight in the net."
It was a pivotal moment not just in the game but also in Everton's season after a miserable few months at the beginning of the campaign.
They have lost only twice in the league since November but Europe is now out of reach.
Round said: "We are very disappointed as we wanted to win today to keep the pressure on.
"We felt after Stoke's defeat last week they would be in an aggressive mood and determined to show everyone it was a one-off.
"We were hoping to take control of the game in the last 30 minutes but unfortunately we could not quite do it.
"We are determined to be in Europe every year. That's the ambition of the club. We want to be in the Champions League if not the Europa League. It does test your resources but we want to be in these competitions.
"We had a disappointing start with key players missing. We have been on an excellent run of form. We have not lost in 10 and that bodes well for next season."
Round admitted Everton missed the services of Steven Pienaar, who was sidelined through injury.
He said: "Steven is a quality player, who has been in great form. He just rolled his ankle in training. It is nothing serious."
Stoke manager Tony Pulis was pleased to see his side keep a clean sheet following the 7-0 mauling by Chelsea last weekend.
It could have been even better for his side had Rory Delap not missed a gilt-edge chance shortly after half time.
He side-footed his effort wide of the post when it seemed easier to score following a cross from Matthew Etherington.
Pulis said: "We have a great bunch of lads. It is a good place to be at this club. We do not want players who think they are doing us a favour.
"The result at Chelsea was a massive disappointment. Our away form has been brilliant, we have been really solid. We showed a response today.
"We hope we have the opportunity to move people out and bring people in. That has always been the case.
"We cannot be making great strides. You cannot be too quick. We will be working as hard as we can to take this club on."
