Sir Alex Ferguson is looking forward to locking horns with Marcelo Bielsa for the first time at Old Trafford aware that the wily South American has produced the best Athletic Bilbao side in years.
Manchester United entertain a team currently fifth in La Liga, who have also booked a Copa del Rey final appearance against Barcelona in addition to their Europa League conquests.
And for that Ferguson believes they have to thank 56-year-old Argentinian Bielsa, who spent a decade coaching first his own country and then Chile at the 2010 World Cup. The Scot said: "I admire his work because I see the emergence of a very good Bilbao side."
He added: "They are very determined and organised, with a great belief in themselves. That is the hallmark of their coach. He has instilled these qualities in his team.
"We know how difficult a game it is going to be for us. This is the best Athletic team I have seen for some years."
So good in fact Ferguson believes United must shake off their European lethargy if they are to reach the quarter-finals.
Ferguson accepts his side never recovered from tossing away a two-goal lead against Swiss outfit FC Basel on Champions League matchday two, a further home draw with Benfica helping to condemn them to a group stage exit for the first time since 2005.
But United have found it no easier in the Europa League, where they almost contrived to get knocked out despite at one stage boasting a three-goal aggregate lead over Ajax.
The Red Devils chief accepts if his side want to prolong their stay in the competition, they must do better, especially as they are now facing a team that is fighting for Champions League football.
"It is a game in which we need to waken up," said Ferguson. "Some of our European form this season has been disappointing."