Birmingham: The change of ball during England's loss to Sri Lanka in the group stages has apparently cost Pakistani umpire Aleem Dar an opportunity to be an on-field official in tomorrow's ICC Champions Trophy final.England captain Alastair Cook was unhappy with Dar for changing one of the match balls in their defeat to Sri Lanka at The Oval last week, leading to speculation of ball tampering.And the British media speculated that the ball change incident might be a reason behind ICC's decision to exclude Dar from on-field duties."England have been spared one potential concern in the Champions Trophy final with Aleem Dar relegated to the peripheral fourth umpire role," a report in the 'The Guardian' said today."Dar's role as fourth umpire will be purely supportive - one of his official roles is to make sure the batteries are working in the light meters," it added.Kumar Dharmasena and Rod Tucker have been named as the on-field umpires for tomorrow's final between India and England, while Bruce Oxenford will discharge the duties of the third umpire.