Managers are often judged on their ability to make game changing substitutions at just the right time. When the pressure is on, the best gaffers, keep a clear head and shuffle their pack with devastating effect.
Prime example: With his Manchester United team trailing 1-0 to Bayern Munich in the 1999 Champions League Final, Sir Alex Ferguson introduced Teddy Sheringham and Ole Gunnar Solskjaer.
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United looked dead and buried, before Sheringham netted an equaliser and then glanced a header onto the boot of the 'baby-faced assassin', who showed no mercy to clinch the European Cup in dramatic fashion.
In that same year West Ham's Academy director Tony Carr guided the Hammers to FA Youth Cup success with a team featuring the likes of Joe Cole and Michael Carrick.
In this video Carr explains his techniques for preparing a sub physically and mentally for action.