LONDON, Feb 19 (Reuters) - British hopes of Champions League glory come up against harsh realities this week when Liverpool visit holders Barcelona and Celtic host AC Milan in the last 16.
The ties form part of a five-pronged British assault on the world's most coveted club trophy, with Premier League leaders Manchester United at Lille and champions Chelsea in Porto.
Arsenal, like England's other group winners, are also away in their first leg tie - at PSV Eindhoven.
Arguably the most prestigious tie is at the Bernabeu, where Real Madrid host Bayern Munich on Tuesday in a game between two clubs who have amassed 13 European Cups between them.
French hopefuls Olympique Lyon, one of the competition's most entertaining sides in recent years, are at AS Roma, while Italy's runaway league leaders Inter Milan host Valencia.
Liverpool's Spanish manager Rafael Benitez knows Barcelona will be a formidable obstacle for his side and that avoiding defeat at the Nou Camp will be the objective on Wednesday.
Liverpool's preparations on a training camp in Portugal have been overshadowed by newspaper reports of late-night drinking by some players - prompting a statement from Benitez.
He met the squad on Sunday and 'made it absolutely clear to all of them the responsibilities that come with playing for this club and the way they are expected to conduct themselves both on and off the pitch.
'The players worked extremely hard at last week's training camp, but we will take disciplinary action and fine any of them who are found to have breached club rules during our stay in Portugal,' he said on the club website.
A bigger problem awaits the 2005 European champions fro Merseyside on the pitch, with Barcelona striker Samuel Eto'o expected to be available along with Ronaldinho and now Argentine playmaker Lionel Messi who is back after injury.
Messi looked sharp as a second half substitute for the Liga leaders in Sunday's 2-1 defeat at Valencia.
'I felt good while I was on and was pleased with my performance but obviously not with the result,' he told Radio Marca.
'Wednesday's game is completely different. We are looking forward to it, as it's at home. I hope we can get a good result but we'll stay calm because it is over two legs.'
Milan, six-times European champions, can be expected to keep their cool against a Celtic side who will need to make the most of home advantage and weakened opponents on Tuesday.
Carlo Ancelotti's side are short of strikers, with the injured Filippo Inzaghi and cup-tied Ronaldo unavailable.
The manager has had to plunder the youth side to make up the numbers, with teenager Davide Di Gennaro joining the squad without a Serie A appearance to his name.
Chelsea coach Jose Mourinho will be well-briefed, though, about his opponents when they take on his former club Porto, who he guided to the Champions League trophy in 2004.