Cup football appeals to the fans' sense of melodrama. All can be won or lost in an instant. Luck plays a big part, so does the referee.

This week controversial refereeing decisions altered the course of ties in each of the two main domestic cup competitions. Neither was intrinsically wrong according to the laws of the game, but both, it could be argued, were unwise.

At the end of Sunday's goalless and largely soulless FA Cup encounter between Wimbledon and Wrexham at Selhurst Park the referee, Steve Dunn, was approached by what appeared to be an agitated Teletubby. This was Joe Kinnear, the rotund, bobble-hatted Wimbledon manager, who was angry because Dunn had blown the final whistle after Neil Ardley had taken a corner but before Marcus Gayle had headed the ball into the Wrexham net.

Most of Kinnear's complaints about referees are unjustified but on this occasion he had a point. If Dunn's stopwatch indicated that time would be up the moment Ardley took the kick it would have been prudent to end the game before the corner had been taken. But if Dunn did tell the Wimbledon player that there still two minutes to go then he blew the final whistle prematurely.

An extract from the official FIFA report on the 1978 World Cup, when a similar incident occurred, supports this line of argument: "There are views that the game should be conveniently and tactically ended as the ball goes out of play, even though this is slightly before the end of the game, or that the game should be extended to see the outcome of immediate play after the restart."

In that instance the referee concerned was Clive Thomas, whose final whistle in Mar Del Plata arrived a fraction of a second before Zico headed in from a corner and denied Brazil a 2-1 victory over Sweden. The Brazilians went nuts, of course, but the game had entered stoppage time, it was the last of three successive corners, and seconds had been wasted getting the kicker to put the ball in the arc.

FIFA appeared sympathetic to the referee, noting that "some defenders had stopped playing on hearing the whistle and before the ball entered the goal". Later, however, Thomas revealed that the following day a World Cup official had told him he should have awaited the outcome of the corner before ending the match, adding that he would not be given another game in the tournament.

Thomas, a good referee but with a showman's tendencies, a cross between Solomon and Cecil B De Mille, declared this week that he had been waiting 20 years for another match to be ended in similar circumstances. However, the recurrence has done nothing to alter the view that both controversies could have been easily avoided with a bit of common sense.

Early in the 1970 World Cup El Salvador were holding the host nation, Mexico, to 0-0 in the Aztec Stadium. The first half was in stoppage time when the ball ran into touch in the Mexican half and the linesman signalled a throw to El Salvador, who moved upfield. But the Egyptian referee, Aly Kandil, awarded a free-kick to Mexico, who took it quickly and scored before the opposition knew what was happening.

In protest, El Salvador refused to restart the match. The referee had to retrieve the ball from the net and bring it back to the centre spot. When he insisted they kick off El Salvador hoofed the ball into the crowd, and by then it was half-time. Mexico eventually won 4-0.

While Kandil had been entitled to overrule the linesman he was guilty of bad refereeing in that the decision had not been made clear to both teams. Middlesbrough's winning goal in stoppage time at the end of Tuesday's League Cup quarter-final at Reading followed similar confusion.

There had been a multi-player fracas in the centre circle, following which the referee, George Cain, appeared to give Reading a free-kick. But the kick was then awarded to Middlesbrough, taken swiftly, and led to Craig Hignett scoring the winner. It might be argued that the scuffling players had contributed to the situation but this was still a case of the referee's indecision being final.

When Kandil refereed a match at Ayresome Park during the 1966 World Cup he emerged from Marks and Sparks in Middlesbrough as a confirmed sockaholic. Thirty-two years on and Middlesbrough have profited from a decision with a hole in it. For Cain read Kandil in the wind.