Soccer/ Uefa Champions League Semi-final, first leg: There is something in Manchester United's DNA that means they never do things the easy way, and tonight's Champions League semi-final against Milan promises to test their powers of endurance to the limit.

Never before has Alex Ferguson's team gone into such a big match so handicapped by the loss of key players, with confirmation last night that the Premiership leaders will be missing their entire first-choice defence.

Ferguson's admission that Patrice Evra will be fit enough only to be a substitute, at best, means United will go into their first semi-final for five years with a completely reconfigured defence already missing Gary Neville, Nemanja Vidic and Rio Ferdinand.

Uefa's statistics show Milan have had more shots on goal in this season's competition than any other side, and Old Trafford will be filled with apprehension to learn a fringe midfielder, Darren Fletcher, will play at right-back.

"Thanks for reminding me," Ferguson observed ruefully when asked whether he was concerned Wes Brown, so outplayed by Middlesbrough's Mark Viduka on Saturday, was the only recognised centre half available. Ferguson has no time for self-pity and he stubbornly insisted he was "happy with the squad". Yet United, in his own words, are "down to the bare bones" and in the midst of "an injury crisis of major proportions".

John O'Shea, now regarded at Old Trafford as a midfielder, shared Brown's discomfort in the centre of defence against Middlesbrough, and a visit to United's training ground yesterday inspired only foreboding given there were only 10 senior outfield players going through the drills. Evra was restricted to light jogging alongside Vidic, Kieran Richardson and Louis Saha. Mikael Silvestre and back-up defender Craig Cathcart are out for the season. Ferdinand and Park Ji-Sung await specialist reports and Neville, out since March 17th, was not even kitted out.

The first question for Ferguson at his press conference was whether he had enough players to name a complete squad. "Of course we have," he responded testily. Later, however, he admitted it would be a struggle to name "an adequate bench".

While Milan's substitutes will include the likes of Cafu, Alessandro Costacurta and Filippo Inzhagi, United's back-up options incorporate Dong Fangzhou, Chris Eagles, Kieran Lee and David Gray.

If United get past this richly experienced Milan side over two legs it will be a feat to rank alongside any of Ferguson's achievements, not least the 7-1 humiliation of Roma in the last round. Milan are in their fourth semi-final in five years and have eight players who have at least one Champions League winner's medal and, in Clarence Seedorf's case, three.

Much of the build-up has concentrated on whether Milan's defence - derided as "dinosaurs" on the sports pages of La Repubblica - can cope with the pace and penetration of Cristiano Ronaldo and Wayne Rooney. It is an overly simplistic theory, however, and Ferguson does not believe the average age of Carlo Ancelotti's back four (32.2 years) to be a major disadvantage to a club that prides itself on parsimonious defending. United's manager recalled Paolo Maldini's man-of-the-match display in Milan's 2-0 win at Bayern Munich in the quarter-finals. "He played the entire 90 minutes without making a tackle," he enthused about a 38-year-old he regards as the most intelligent defender in football. "It's an art."

Ferguson's defensive resources are so sparse he was not in any position to start picking out possible Milan weaknesses, but he was as upbeat as he possibly could be. "I don't have any fears about it," he said. "I see the mood in the camp and it pleases me. I'm always looking for signs at this time of the year about nerves. But I see none. Yes, we have concerns about one or two injuries and you do miss players such as Ferdinand and Neville and Saha. But we also have important players playing. On Saturday we saw some anxiety and some bad decision-making in the last third. But no one was hiding."

He reflected that Fletcher and O'Shea - players frequently maligned by United's fans - were outstanding against Roma, although he quickly pointed out that was a "once-in-a-lifetime" result. Nothing so spectacular can be expected tonight when, despite United's natural tendency to attack, the trick will be not to concede an away goal.

• Guardian Service

Manchester United v AC Milan

Venue: Old Trafford

Kick-off: 7.45

On TV: RTÉ 2, UTV

Referee: Kyros Vassaras (Greece)