The 60-second spot, which breaks on Sunday, was created by Bartle Bogle Hegarty and will run in the half-time break during Sky Sports 1's coverage of Sunday's Charity Shield curtain-raiser between Premiership champions Chelsea and FA Cup holders Liverpool.
In the ad, titled 'Shower', McGrath steals the shirt of his Arsenal idol Thierry Henry after locking him in the dressing room shower, pulls it over his rotund frame and then heads for the pitch to play in his place.
The 'Win a contract' promotion rewards Barclays customers by entering them in a prize draw every time they use their Connect current account debit card between August 18 and November 3.
The prizes are a 'contract' at every Barclays Premiership club, which includes a 拢10,000 signing-on fee, the chance to play at your club's ground, a signed shirt and a number of other prizes related to the winning entrant's club.
People who do not bank with Barclays can enter the draw once through the Winacontract.co.uk website. Barclays customers registering at the website stand the chance of winning a replica shirt every 90 minutes.
Jim Hytner, Barclays' group brand and UK banking director, said: "Sadly, this is the only opportunity many of us will have to win a contract with the Barclays Premiership team we support.
"Barclays Premiership sponsorship is about adding value to the game for fans, and there's no better way to do this than give people the opportunity to sign for their team."
The BBH's creative team behind the ad were Simon Parker and Richard Glendenning, with creative director Russell Ramsey. The spot was produced by Sally Campbell and directed by Peter Cattaneo.
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