Manchester United could go into their last 16 second leg Champions League tie against AC Milan at Old Trafford on Wednesday without star striker Wayne Rooney.

United manager Sir Alex Ferguson was angry the in-form Rooney, who has scored 29 goals already this season - including two in the first leg against Milan - played for England in last week's friendly win over Egypt at Wembley.

It was his second appearance in four days on the much criticized pitch after he came off the bench to lead United to victory in the League Cup final against Aston Villa and did little for his long standing knee problem.

Rooney was absent from the 1-0 win at Wolves on Saturday that returned the reigning champions to the top of the Premier League table and Ferguson confirmed he could miss the match against Milan, where United will kick-off holding a 3-2 advantage from the first leg in Italy.

"He's a doubt for Wednesday so that's a big blow," Ferguson said of Rooney.

United will also be without Michael Carrick after the England midfielder was sent off late on in the first leg win at the San Siro.

Meanwhile, Wednesday's game comes too soon for Ryan Giggs, who will have the cast on his fractured arm removed in the early part of the week.

Ferguson believes scoring at Old Trafford will be key to his side's hopes of reaching the quarterfinals.

The United manager is still frustrated at the manner in which his players left Milan with just a one-goal lead.

After falling behind to an early Ronaldinho strike, United hit back through Paul Scholes and two goals from Rooney before Clarence Seedorf struck late on to give Milan hope despite the Red Devils' first win in the San Siro.

Champions League finalists for the past two seasons, United have never been knocked out in the second leg when they have returned to Old Trafford with a lead at the halfway stage of a tie.

And they have failed to score just once in seven European games this season, when a fringe side lost 1-0 at home to Besiktas.

Ferguson feels causing Milan problems, rather than sitting on their advantage, will be vital if United, champions of Europe under his guidance in 1999 and 2008, are to reach the last eight.

"I think that second (Milan) goal gave us all a wake-up call," he said. "If we score we'll go through. We'll threaten to score and we'll certainly get chances in the game but we've just got to make sure that we take them."