Arsene Wenger has seen it coming before and at 10.30am he will steel himself again for what a part of him may consider as the brutally inevitable. Barcelona lurk in the Champions League last-16 draw and being paired with them would represent the ultimate sanction for his Arsenal team’s failure to get through as group winners.

A quickening heartbeat, though, will hardly be Wenger’s sole preserve.

With Chelsea and Manchester City strewn by the wayside after disastrous group-stage campaigns, Manchester United are the Premier League’s only other surviving representative in Europe’s elite competition and Alex Ferguson might find his team’s seeded status counts for nothing.

United made amends for last season’s group-stage failure by wrapping up top spot in Group H after four ties, yet dangerous fish circle in the bowl of unseeded runners-up, most notably Real Madrid. A pairing with the Spanish champions would mean a return to United for Cristiano Ronaldo, while it would also pit Ferguson against Jose Mourinho and evoke memories of the Portuguese manager’s celebratory dash along the Old Trafford touchline in 2004, during his time at Porto.

Unlucky draw

Real would be an unlucky draw for United but Milan or Shakhtar Donetsk, the Ukrainian club who helped to make Chelsea the first holders to exit at the group phase, would also lead to cursing at Old Trafford.

Ferguson’s percentages at the draw in Nyon, though, look slightly better than Wenger’s.

It is easy to imagine United would take Porto, Valencia or Celtic, whose fairytale qualification was memorably embossed by the home win over Barcelona which featured joy, bedlam and a rock star’s tears.

If a third knockout-stage meeting with Barcelona in four seasons is the nightmare scenario for Arsenal, then Bayern Munich or Borussia Dortmund, arguably the team of the group phase, would also be testing on an intimidating scale.

Dortmund’s unbeaten advance on top of a group that contained the champions of Spain, the Netherlands and England was marked by eye-catching football.

Arsenal’s other possibilities are the money-flushed Paris St-Germain, who have spent roughly €250m in fees alone over the past three transfer windows; Juventus, the Serie A invincibles of last season and Malaga, the tournament debutants who won so many admirers in Group C when they finished above Milan and saw off Zenit St Petersburg.

Arsenal cannot face United in the last 16 due to the country-protection rule and no team can meet an opponent from the same group phase.

Barcelona, Real, Bayern and Dortmund are listed by bookmakers as the tournament favourites. In that order.

But the pool of talent is wide. Shakhtar, for example, have players who would get into most Premier League teams (Willian, Alex Teixeira, Fernandinho) while PSG's emergence, on the back of their wealthy Qatari backers, has altered the landscape.

It speaks volumes for the competitiveness of the Champions League that Real and Milan could only qualify as runners-up in their groups.

There has been a glorious unpredictability to the competition so far. Neil Lennon described his Celtic team's progress as akin to a "miracle" while Galatasaray's passage, helped by Burak Yilmaz's goals, has fired passions in Turkey.

Today will also determine the ties for the last 32 and final 16 of the Europa League.

The Premier League is represented in the shape of Chelsea and Liverpool (seeded); Tottenham and Newcastle (unseeded). The Premier League clubs cannot meet in the last 32. The Champions League draw, however, promises the drama. Guardian Service