United open with a home game against Ossie Ardiles' Croatia Zagreb tonight, but Ferguson is in no doubt who will provide the biggest threat to his side's Champions' League supremacy, even if they have not already weakened their own grip by a lack of spending on eligible recruits.
Sir Alex was typically blunt yesterday as he surveyed the European opposition he knows well after years of campaigning at this exalted level. Asked who constitutes the biggest danger to United this season, he said: "Barcelona, definitely."
When United hoisted the European Cup in Barcelona last May, the next step was supposed to be "moving on to another level". But while United have fumbled in the transfer market, Barcelona have dug into their resources to strengthen their squad to levels that United can only watch and admire.
"I think Barcelona were unlucky last season with the injuries they had," Ferguson said. "[Winston] Bogarde was out for a season and [Miguel Angel] Nadal was missing. Louis van Gaal has bought another three or four players, the two De Boers, Dehu, and has Patrick Kluivert available. He's got a squad together.
"Van Gaal has recognised what we've all recognised - you need a good pool of players. Barcelona have got two teams, and I mean two teams of internationals. I look at them as a threat. I hope we get them in the final. I'm not being presumptuous, I just have to dream."
While Barcelona have two teams, United barely have one. Their belt-tightening in the summer has left them vulnerable now the squad are beset by injuries. The supposed biggest club in the world have had a miserable time in the acquisition of players who can play in Europe. Four have been signed, including two keepers, one South African squad man and a Frenchman from the fringes of Internazionale's squad. Unless Mark Bosnich makes an unlikely appearance or Quinton Fortune comes on from the bench, none of that quartet will figure tonight at the start of their defence of the European Cup.
Questions about the signings have not been raised yet as United dominate the Premiership, but domestic results disguise an underlying division between the manager and the board. The current crop of crocks - a total of eight players - was unforeseen. However, Ferguson wanted more cover just in case. His recent frantic moves for a centre-half have highlighted the growing concerns within Old Trafford.
One player suffering more than most is Gary Neville who will be absent for two months. "It's a complete tear of his abductor," Ferguson said.
So Michael Clegg will make his European debut against Zagreb at full- back in a back four of Phil Neville, Henning Berg and Jaap Stam.
Denis Irwin has recovered from his Achilles injury and should be on the bench, while Bosnich is fit following his hamstring problem and will challenge Raimond van der Gouw for the keeper's jersey.
Ferguson is considering a change of formation, although he may stick with his usual 4-4-2 line-up and deploy Jonathan Greening on the right side of midfield with David Beckham in the middle. "I just have to make a decision about the content of my midfield, whether I should stick with four or take the risk of going with three and play with three up front," the manager said. "We have one or two problems and it's not an easy game for us, but it won't be for them either."
Ferguson has great faith in the mental strength of his squad and United are helped by the fact that their qualifying group, starting with Zagreb and followed by Sturm Graz and Marseilles, is hardly a testing one.
Ardiles, meanwhile, is feeling the pressure after a poor start to the season, although Saturday's 4-0 win over Istra has relieved matters slightly.
"It seems that since I first came here, every week someone asks me is my position sure," the former Tottenham, Newcastle and Swindon manager said. "After we drew the league game against Rijeka, I didn't sleep the whole night because I was afraid for my position."
Ardiles will, however, will stick by his attacking principles tonight. "We are in show business and people pay the ticket prices - and those prices are not cheap - and we must entertain them," he said.
"We're not coming here to defend for 90 minutes and any team that comes to Manchester United to do that will lose anyway. We are going to try to push forward and counter-attack at every possible opportunity."
Glenn Moore; Champions' League schedule, page 24Reuse content