United strolled through their group, beating Rangers and Panathinaikos home and away and triumphing over Stuttgart at Old Trafford in the final group game after losing to Felix Magath’s side in Germany.

The Red Devils have reached the knock-out stages of this competition in every season since 1996-97, famously winning the competition to complete the treble in 1999.

Porto finished second in Group F behind Real Madrid and beat Celtic 3-2 to win the UEFA Cup last season and will host United at the Estadio Dragao in the first leg on February 24 or 25, with the return at Old Trafford scheduled for March 9 or 10.

Chelsea will face German league leaders Stuttgart in the first knock-out stage.

Stuttgart, who have conceded just three goals in 15 Bundesliga matches, finished behind Manchester United in Group E but beat Sir Alex Ferguson’s side at the Gottlieb-Daimler Stadion.

Claudio Ranieri’s expensively-assembled squad impressed in the group stages, with a home defeat to Besiktas the only real blip.

The Blues beat Lazio home and away en route to topping the group, with a 4-0 victory over the Italian side at the Stadio Olimpico particularly gratifying for Ranieri and his team.

History is on their side, with Chelsea having beaten Stuttgart to win the European Cup Winners’ Cup in 1998.

Arsenal will play Spanish side Celta Vigo after being in danger of missing out on the knock-out stages – or even a UEFA Cup place – after taking just one point from their opening three group games.

However, a late Ashley Cole header helped them beat Dynamo Kiev 1-0 at Highbury and that proved the turning point as Arsene Wenger’s men then hammered Inter Milan 5-1 at San Siro.

They completed the job on Wednesday night by seeing off Lokomotiv Moscow 2-0.

Celta Vigo progressed with a surprise win over a below-strength AC Milan side to secure second place in Group H.