Bolton boss Sam Allardyce said El-Hadji Diouf's dismissal after eight minutes undermined his team's hopes of beating Arsenal in the FA Cup.
"We played Arsenal at a good time, fatigued and demoralised after their Champions League exit," said Allardyce.
"We would have had more chances as the match went on but that did not happen as we only had 10 men.
"We undid ourselves with Eh-Hadji getting sent off but our 10 men gave Arsenal's 11 a hell of a game."
Arsenal scored the only goal through Freddie Ljungberg but Allardyce felt his team should have been awarded a foul earlier in the move.
"We felt Tal Ben Haim won the ball cleanly off Dennis Bergkamp, who brought Tal to ground and it was picked up by Robert Pires," he added.
"It was a major factor and a major decision in us going out of the Cup."
But the Bolton manager was critical of Diouf, who was sent-off for elbowing Arsenal goalkeeper Jens Lehmann.
Arsenal's goalkeeper approached Diouf as the Bolton striker made his way towards the referee to appeal for a foul.
"Lehmann had no need to go up to him," added Allardyce. "He has gone over to intimidate Diouf, the lad has reacted and got himself sent-off.
"I think as always the goalkeeper has made a meal of it and used gamesmanship to get Diouf dismissed but if you lift your hands you have to go.
"To win the cup you need the rights breaks at the right time - and Arsenal got those breaks."