Chelsea striker Diego Costa was at the centre of a biting controversy as Romelu Lukaku wrecked what was left of his former club's season to secure Everton's place in the FA Cup semi-finals at Wembley.
Costa appeared to make contact with the neck of Everton's Gareth Barry at the end of a running battle between the pair as he received his first red card in English football.
Everton were leading by two goals by Lukaku, including a superb 77th-minute solo goal, when Costa was sent off by referee Michael Oliver.
A Chelsea spokesman said: "Diego spoke to club officials and expressed regret over his reaction to the challenge from Barry that led to his red card.
"But Diego was also very clear that he did not bite him at any point during that altercation."
Everton manager Roberto Martinez said midfielder Barry had not complained about the incident - and was more interested in a win that takes his side to a semi-final at Wembley rather than any incident involving Costa.
It was Lukaku's brilliance which decided this stormy quarter-final - and there was still time for Barry to be sent off after receiving a second yellow card for a foul on Cesc Fabregas.
That could not stop the excitement sweeping around a very happy Goodison Park as manager Martinez celebrated a hugely significant victory.