Manchester City boss Sven-Goran Eriksson says his side were denied victory over Blackburn on Thursday by a goal that should not have stood.
Blackburn players question the assistant referee's decision
Rovers striker Roque Santa Cruz headed in to level the score at 2-2, despite David Dunn appearing to be offside.
Eriksson told BBC Five Live: "I discussed the decision with referee Howard Webb and asked about the rules.
"Dunn is stood in an offside position and it seems like the ball was played into him. For me, it was offside."
Initially the assistant referee raised his flag, appearing to rule Dunn offside but changed his mind in the belief that the Blackburn man was not interfering with play.
Fifa's Law 11 states that a player is active, and therefore offside, if he:
plays or touches the ball, passed or touched by a team-mateprevents an opponent from playing or being able to play the ball by clearly obstructing the opponent's line of vision or movements or making a gesture or movement which, in the opinion of the referee, deceives or distracts an opponentgains an advantage by being in a position that allows him to play a ball that rebounds to him off a post or the crossbar having been in an offside position, or playing a ball that rebounds to him off an opponent having been in an offside position
And Eriksson believes Rovers' second goal of the match broke that ruling.
"The ball seems to be played in to Dunn, and my defenders and goalkeeper react to that ball first. Dunn tried to head the ball but he didn't reach it," the Swede said.
"The ball goes over and then it is too late for my players as Santa Cruz comes from an onside position and scores a goal.
"I think it should be offside but the referee has defended his opinion and if that is the rule, then we have to accept it. We cannot do anything about it now."
Eriksson's view appears to be supported by Graham Taylor, who was covering the game for Five Live.
The former England manager said: "As I see it, Dunn tried to head the ball further into the penalty box while he was in an offside position. I cannot grasp how he can be considered to be inactive.
The assistant referee realised he had put the flag up too early and he was big enough to admit that
"As far as I'm concerned, Dunn is offside, he tries to head the ball and misses it - that doesn't matter; he is active.
"When I have read the offside law, it seems to read all right. But when you are watching a game, and things happen, it doesn't seem to make sense."
However, Blackburn manager Mark Hughes feels the decision to allow the goal to stand was the correct one and praised the assistant referee for his actions.
Hughes said: "I saw the flag going up early and I thought the goal had been disallowed.
"I think the assistant referee put his flag up for David Dunn's position but he wasn't interfering with play.
"The assistant referee realised he had put the flag up too early and he was big enough to admit that.
"We are pleased that he was strong enough to realise his mistake early and correct it."