STEVE McCLAREN has drawn on his experiences of Manchester United's treble triumph of 1999 in an attempt to avoid a fruitless end to Middlesbrough's assault on a cup double.

Boro head to Charlton tonight with McClaren facing an 'enormous selection headache' as he purrs over whether to include Mark Viduka in his starting line-up after bagging three goals in three league games.

The likelihood is that, although tempted to play the Australian at the ground where he scored a sensational 25-yard screamer this month, McClaren will leave Viduka on the bench.

Jimmy Floyd Hasselbaink and Aiyegbeni Yakubu, the manager's first-choice pairing in recent months, are expected to be handed the chance to break down the Charlton defence tonight.

But, having experienced just how important the squad system is during his days as Sir Alex Ferguson's right-hand man at Manchester United, McClaren knows he has to try to keep everyone happy.

The Boro boss was one of the men charged with the responsibility of telling many of United's players that they were not going to start the European Cup and FA Cup finals seven years ago.

McClaren, though, points to the way two of those, Teddy Sheringham and Ole Gunnar Solskjaer, emerged from the bench in the Nou Camp to turn a 1-0 deficit to Bayern Munich completely around.

He is keen to ensure team spirit remains intact as Boro look to edge into the semi-finals of the FA Cup tonight.

"The biggest thing I have learned from 1999 is that it is a squad game," said McClaren. "The training has to be geared to everybody so that when called upon they are ready to play.

"In Barcelona they all contributed. Nobody accepts being left out and I don't want them to. They all want to play in every game and ideally I want to play them in every game, but it is an impossibility.

"People have been professional in accepting decisions, maybe not liking it, but they have got on with it. Mark Viduka is the perfect example of somebody who has got on with it, trained hard and was ready when he came in.

"He is one of those players who epitomises what we are trying to do and has responded by showing his professionalism. When given the opportunity he has not let anyone down and scored three in three."

It is Viduka's form in the Premiership - after his goals against Birmingham, Charlton and Blackburn - that has raised the question of who should be starting up front for Boro.

Even though Yakubu is the club's top scorer with 19 goals he, in theory, is the most out of form, having scored just one in his last six appearances. Hasselbaink has nine in nine starts.

Regardless of his team selection, McClaren admits Charlton provide a huge hurdle to overcome.

He is keen to avoid a replay, as Boro will be taking part in their 48th game of the campaign at the Valley this evening.

"They are capable of scoring with Darren Bent up front and a home draw is a massive advantage, it is not going to be easy," he said.

"I think our schedule is already very heavy and winning there would be ideal. But if a replay is what it takes to get to the semi-final, I will take it."

After tonight's trip to the capital, Boro face Bolton at the Riverside on Sunday before travelling out to Switzerland for the first leg of the UEFA Cup quarter-final tie with Basel.

Chris Riggott is struggling with a calf problem picked up at Blackburn on Saturday and Andrew Davies is cup-tied. Stuart Parnaby is in contention after recovering from a hamstring injury.

Read more about Middlesbrough here.