5 of the greatest Champions League Round of 16 upsets

2. Porto 3 - 2 Manchester United: 2003-04

The other dash: Costinha takes off after his injury-time goal at Old Trafford2003-04 Champions League saw a certain Portuguese manager announce himself to the English footballing world with a legendary dash at Old Trafford following Costinha's last-minute equalizer that eliminated the Red Devils from the competition.

Some 15 years later, Jose Mourinho is the manager of Manchester United but the Old Trafford faithful haven't forgotten how he led F.C Porto to victory over Manchester United in the Round of 16 stage of the Champions League all that years ago.

Mourinho had just won the UEFA Cup with Porto the previous season and the grittiness of his talented side came to the fore in the first leg at the Estadio Dragao. Comprised of the likes of Ricardo Carvalho, Nuno Valente, Deco and Benni McCarthy, the Porto squad was way more than just an average side edged on by their manager.

Despite Quinton Fortune giving United an early lead, two goals from McCarthy saw Porto win the leg 2-1 over ten-men United who also had Roy Keane sent off.

United could win the tie with an unanswered single goal victory in the return leg and they seemed right on track when Paul Scholes headed in from close range to give United control in the tie on away goals.

Deep into second-half injury time, however, United keeper Tim Howard could only parry McCarthy's freekick and Costinha was the quickest to pounce on the loose ball. A second later, the ball was in the back of the net and both Costinha and Mourinho had taken off on their victorious dashes.

Porto would complete their dream run in glorious fashion, eliminating Lyon, Deportivo La Coruna and finally Monaco to become the last underdog to win the Champions League.