The eight group winners will be paired against the eight runners-up in two-legged ties that will be played in February. Manchester United, who won Group H, cannot, however, be paired with another club from the same country at this stage of the competition. Thus, there will not be a battle of England against Arsenal, who finished runners-up in Group B. United could, however, face Celtic, who were runners up in Group G. United could also be paired with Porto, Milan, Real Madrid (who they were picked to face in a rehearsal draw yesterday), Shakhtar Donetsk or Valencia. Sir Alex Ferguson's side won their first four group games, before two relatively meaningless defeats.

For Arsenal, the cost of not winning their group becomes apparent at 10.30am today. The list of potential opponents is a who's who of European powerhouses. It could be Paris St-Germain, Barcelona, Juventus, Bayern Munich, Borussia Dortmund or Malaga. However, Arsène Wenger will know only too well of the calming nature a Champions League run can have on a troubled domestic campaign.

Celtic and manager Neil Lennon similarly face giants wherever they turn. They could take on any of Arsenal's opponents, apart from Barcelona. Instead, they have Schalke and United to contend with. In their favour is the fact that Celtic Park is a European fortress that few clubs in the draw will feel particularly pleased about heading to.

Beating Barcelona has been the story of this year's competition by a country mile. By lunchtime today, however, some of European football's true giants will be concerned about their very future in the competition.