The knockout stage of the 2002–03 UEFA Champions League ran from 8 April 2003 until the final at the Old Trafford in Manchester, England, on 28 May 2003.
The team that has the higher aggregate score over the two legs will progress to the next round.
In the final, the tie was played over just one leg at a neutral venue.
If scores were level at the end of normal time in the final, then 30 minutes of silver goal extra time was applied, whereby the team who leads the game at the half-time break during the extra period would be declared the winner.
For the Milan v Internazionale tie, both clubs played their home leg in the same stadium (the San Siro), but Milan were the designated away side in the second leg, and thus won on away goals.