It might have prompted much amusement in August had someone suggested that Manchester United would be sauntering towards a second treble with the fringe members of their squad at the helm, but, as the season enters its final weeks, Sir Alex Ferguson’s belief that success will hinge on the performances of such players has never rung truer.

Ferguson had claimed before the 2-0 victory over Sheffield United in the Barclays Premiership on Tuesday evening that he was “more convinced than ever that if we are going to win something it will be because of the players who have waited patiently on the bench”, and, as the final whistle sounded at Old Trafford without one of his first-choice defenders on the pitch, the United manager’s faith in his squad appeared to have been vindicated.

Rio Ferdinand and John O’Shea are expected to return for the Premiership game at home to Middlesbrough on Saturday, but their recovery from groin and calf problems respectively has been partially offset by an injury to another defender, Patrice Evra.

The left back underwent a scan yesterday on a calf problem that prompted his withdrawal after only 21 minutes against Sheffield United and it is doubtful that the Frenchman will be fit in time to face Middlesbrough.

Evra’s absence would represent another blow to United, who have already lost Nemanja Vidic and Mikaël Silvestre for the remainder of the season and are sweating on the fitness of Gary Neville, the England defender, before the first leg of their Champions League semi-final, first leg against AC Milan at Old Trafford on Tuesday.

Of equal concern is the injury situation of Louis Saha. Ranko Stojic, Saha’s agent, told The Times yesterday that the France striker should have recovered fully from a hamstring problem “in the next seven to ten days” and that his client was confident that he would be available for the second leg in Milan on May 2.

Saha was initially ruled out for four weeks after damaging his left hamstring during shooting practice on March 6, but, despite Ferguson insisting that the player would be fit for the Premiership game against Blackburn Rovers on March 31, the Frenchman has made only one substitute’s appearance in the six weeks since he suffered the injury.