Wigan Athletic reached the FA Cup final for the first time in their history when they beat Championship side Millwall 2-0 at a soggy Wembley in a match overshadowed by violence which broke out when Millwall supporters began fighting each other.
Goals from Shaun Maloney after 25 minutes and Callum McManaman after 78 minutes allowed Wigan to forget their relegation worries for an afternoon as they finished as deserved winners against the second tier team.
But the match was marred when fighting broke out between Millwall's own fans who traded punches with each other for more than 20 minutes, ignoring their team's efforts on the field.
Television footage showed several supporters bloodied, police using batons, and a child in tears as the trouble continued.
"The policing response was robust and proportionate and 11 people were arrested during the game in connection with the violence that broke out shortly before half time and full time," the Metropolitan police said in a statement. "Four police officers received minor injuries."
The FA called for criminal charges and football banning orders to be brought against those responsible.
Millwall manager Kenny Jackett, in charge of his side for the 300th time, praised his players for their efforts, but said he was unaware of the violence while the match was being played and hence could not comment on the incident.
Wigan manager Roberto Martinez, whose side are two places off the foot of the Premier League table, will meet the winners of Sunday's second semi-final between holders Chelsea and league champions Manchester City when the final is staged back at Wembley on May 11.
They have pulled off some Houdini-like escapes from relegation over the last few seasons, and Martinez said this result would give them heart for the run-in.
"It is a major result for us, you don't usually associate the words Wigan Athletic and FA Cup final in the same sentence," he said.
"Now we must concentrate on the League and make sure we stay up. That is what success will mean to us this season, as well as reaching the Cup final."
Saturday's victory represents a major success for Wigan chairman Dave Whelan, who broke his leg playing for Blackburn Rovers in the 1960 FA Cup final against Wolverhampton Wanderers, an injury that finished his top flight career.
He has overseen Wigan's progress from a lower league club to one that has survived in the Premier League since 2005 and although Wigan had hoped he would be able to lead the team out on Saturday, FA protocol did not allow that.
The club is hoping he can do that at the final next month, and Martinez said: "He is a remarkable man. They should make a film of his life for what he has done for Wigan."
The breakthrough came after 25 minutes following great work in the build-up from Ivorian Arouna Kone, who chested the ball down and then outpaced three men in a powerful run upfield before crossing for Maloney who swept the ball in from close range under the body of Millwall keeper David Forde.
Wigan's second goal also started deep inside their own half after the only period of pressure from Millwall and ended when McManaman rounded Forde to slot the ball into the empty net 12 minutes from time.
The move again involved Kone, who had a superb game playing deeper in midfield than his usual role up front, and for all their organisation, Millwall could not contain him, McManaman or Maloney.
One bonus for Wigan is that even if they are relegated at the end of the season and lose the final, they are likely to be playing in the Europa League for the first time next season as both Chelsea and ManchesterCity are almost certain to finish in the top four and qualify for the Champions League.
Wigan created most of the chances until Millwall began to put their defence under real pressure for the first time with an hour gone when James Henry went close with a direct free-kick and defender Mark Beevers saw a powerful header deflected away for a corner.
"We had 20 minutes when we had to score but couldn't and after that Wigan did and killed the game. But I am very proud of my team," said Jackett, whose side are also battling to avoid relegation from the Championship as they are only three points above the drop zone.
"We now have to avoid relegation because otherwise it will take the gloss off what has been a great run in the FA Cup."
Photograph: Darren Staples/Reuters
Tevez leads City into FA Cup semis, Wigan beat Everton
EPL: Torres sparks rally as Chelsea jump above Spurs
EPL PIX: Chelsea climb to third as Spurs lose again
EPL Photos: Manchester United move closer to title
Newcastle and Wigan assistants fined for clash