McClaren rested all of his big names in preparation for Wednesday’s UEFA Cup final against Seville but the young team he selected produced a mature performance.

All 16 of the squad were English and 10 were under the age of 20 with Lee Cattermole becoming Boro’s youngest ever skipper at 18 – but they were still good enough to hold Fulham until the 84th minute.

With the Cottagers in lacklustre mood – there was nothing at stake on the match and it showed – the game looked to be heading for a draw until substitute David Wheater conceded a penalty.

He brought down substitute Heidar Helguson from behind and the Iceland striker sent goalkeeper Ross Turnbull the wrong way.

Fulham would have been out of sight at half-time had Collins John’s finishing not been so woeful with the Dutch striker missing a hat-trick of chances.

His problems continued after the interval with one gilt-edged chance going begging and it came as little surprise when he was replaced by Helguson in the 56th minute.

McClaren, unveiled as Sven-Goran Eriksson’s successor on Thursday, will now travel to Eindhoven for his final match as Boro manager and the club’s first European final.

Fulham paraded new signing Jimmy Bullard – who completes his £2.5million move from Wigan tomorrow – 10 minutes before kick off and the 27-year-old was given a noisy welcome by home fans.

Wayne Bridge lined up in left midfield and his well-struck corner in the first minute created a chance for Carlos Bocanegra – but the USA defender’s header was off target.

Fulham should have gone ahead shortly after when Bridge picked out a run from Liam Rosenior but his inch-perfect cross to the far post was squandered by John, who nodded wide from close range.

Danny Graham could have edged Boro in front after being set up by James Morrison but he failed to connect cleanly with the ball and his shot drifted wide.

Niemi displayed lightening reflexes to keep out a beautifully-hit free-kick from Adam Johnson but then Boro survived a few anxious moments with Diop and Steed Malbranque having efforts blocked.

Bridge created a chance for John with a well-timed through ball but the Dutch striker stabbed wide with Boro keeper Turnbull rushing off his line.

German right-back Moritz Volz completed a marauding run with a cross to Brian McBride but the striker’s glancing header was well saved by Turnbull.

It had been a lively opening half hour but chances dried up for a spell as the defences tightened up.

John just failed to round Turnbull in the 38th minute after collecting a long ball, although he was not to blame this time as Boro’s alert keeper reacted swiftly.

McBride had another header blocked by a scrambling Boro defence as Fulham tried in vain to break the deadlock before half time.

Boro made a bright opening to the second half with James Morrison easily rounding Rosenior but the midfielder then ran out of space.

Tenacious work from Volz then saw the former Arsenal defender evade two tackles but his final delivery was poor.

Danny Graham was booked in the 51st minute for palming the ball intothe net after just failing to reach Morrison’s cross with his head.

Soon after Volz teed up John but once again he failed to bury the chance, looking far too casual as he attempted to steer the ball past Turnbull, and was then hauled off.

McBride headed a long free-kick from Rosenior onto the roof of the net and then another one wide, but Fulham were not enjoying the same control as they did in the first half.

Graham tested Niemi from an acute angle but then disaster struck for Boro when Wheater hauled down Helguson and the Iceland striker delivered the killer blow.