Roberto Martínez has denied Everton are mentally fragile, arguing that throwing away a two-goal lead against West Ham was down to a set of special circumstances rather than a pattern that has been repeating over a season.

Everton have drawn or lost so many games from winning positions their supporters remain nervous even when the team are in front, yet conceding three goals in 12 minutes against West Ham to end up with another 3-2 defeat was a surprising new low. Romelu Lukaku had a penalty saved at 2-0.

“It would not have happened like that if we hadn’t missed a penalty,” Martínez said. “And we had been playing with 10 men for most of the game. If we had won the game we would have had an incredible boost, being a man down for so long it would have been a great achievement but the penalty affected the whole environment.

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“It is not normal for a team that has conceded two goals in six games to give away three in 12 minutes. We don’t react badly to conceding goals. We have lost a couple of two-goal leads this season but we have learned from that. In normal circumstances we can handle opponents pulling a goal back but against West Ham it was not normal circumstances. It was completely different.”

Martínez and his players face an FA Cup quarter-final against a Chelsea side just eliminated from the Champions League and with the Cup their only route to a trophy. Guus Hiddink beat Everton in the 2009 final in his last spell with Chelsea and will be hoping for at least a return to Wembley before making way for Antonio Conte.

Martínez, too, is badly in need of a lift from the Cup to end the season on a high. It is three years since he established his reputation, certainly on Merseyside, by demolishing Everton at this stage en route to winning the FA Cup with Wigan. He now says, perhaps diplomatically, he has no recollection of that game.

“It is such a long time I can’t even remember,” he said. “All I recall is that we knew it was a big game and we were aware that in coming to Goodison we were coming to a special place to play football. This quarter-final will bring together two teams that know each other really well and it should be another good game.

“We are not going to carry any hangover from the league results into it and I don’t think Chelsea will be too affected by their European exit either. It is a different situation and competition for both of us and we are playing at home.

“The fact we have lost eight matches in the league is obviously not good enough but this is a chance to put some of that right. We have created negative momentum for ourselves at home, where things have gone against us in a way that has not happened in our away games. We have to stop that. This is a one-off game and it could be an important one.”