Manchester United's Famous 1999 Treble
 
The 1998-99 season was the most successful in the history of Manchester United Football Club. United won the FA Premier League, the FA Cup and the UEFA Champions League. This made them the first club from the big five European domestic leagues to complete a Treble of the above 3 competitions. In particular, United went undefeated from December 1998 – May 1999, a run of 33 matches.

United gained a reputation for winning matches after being behind. Some of their more notable come-backs were the FA Cup Fourth Round tie at home to Liverpool, which Liverpool led from the third to the 85th minute, and both legs of the UEFA Champions League semi-finals against Juventus F.C. Most dramatic was the UEFA Champions League final against Bayern Munich win in stoppage time gave United a 2–1 win. It should be noted that United had already gained a reputation for late goals, stretching back many years.

United suffered just five defeats all season; three in the league, one in the Charity Shield and one in the League Cup. They defeated every other Premiership team at least once and were undefeated in the Champions League — Barcelona were the only team that United played in Europe without beating at least once.