Was this the FA Cup QF in 1993 or the league game in 2001? While most of the trouble at the the former seem to centre around the pitch invasion, there was a lot more widespread trouble in the streets before and after the league game in 2001. So much so that I think after that game, the police declared that all pubs around Maine Road would be closed after the game at all subsequent matches right up until the end of that season (however, if you knew where to go you could still get in certain places!). That game wasn't the only trigger. There had been trouble at plenty of other home games that season, particularly the FA Cup match against Coventry, but the Spurs game was the one that broke the camel's back so to speak.