United lost 3-2 at home to Bilbao last week and Ferguson was unreserved in his praise of Athletic.
“I think we saw plenty of evidence last week of an emerging, young team that has got the prospect of doing very, very well,” Ferguson said. “It was an outstanding performance by them, not only just in their ability but their energy was unbelievable, the highest stats of any team that has played at Old Trafford in the last 10 years, in terms of the distance run, and that is great credit to the desire of the team to do well.
“They had a great motivation last week coming to Old Trafford and whether they can sustain that seven days later is difficult to say but we expect that. So I think the most important thing is our performance level has to step up.”
