Leicester City fans hope they have scored a massive victory over one of their oldest rivals - by putting a jinx on their new stadium!
They claim the shirt is set in concrete beneath the main stand, meaning it would cost millions of pounds to dig up.
The builders hope it will act as a jinx every time City travel to The Sky Blues' 32,000-seater home.
Lifelong Leicester fan Steve Grieves, 45, from Glenfield, was among the builders who carried out the stunt.
He said today: "We were working on the site with these Coventry fans and wondered how we could get one over on them.
"We reckon the shirt will be a curse and help Leicester win every time they play there.
"It's going to be there forever because it's not as if they're going to dig up the main stand.
"If I found out there was a Coventry shirt in our main stand at the Walkers Stadium, I would be livid."
Steve was part of a team which spent 11 months helping to build the stadium.
His bosses did not know he was burying the shirt.
The jinx may already be working. Car company Jaguar pulled out of a planned sponsorship deal worth millions of pounds last December.
Bad weather last summer and a fire in January this year hampered construction work - meaning the venue missed its proposed opening date by three weeks.
It meant the club missed out on a glamorous friendly against Spanish giants Barcelona and had to play their first games of this season away from home.
City fans will have to wait until April 17 for The Foxes' first game at the arena to see if the shirt can bring them luck on the pitch.
Fan John Regan, 52, from Wood-gate, Leicester, said: "Coventry are one of our local rivals and I hope this can help us beat them."
Sky Blues fans insist the shirt will have no effect on their team's fortunes.
Peter Andrews, 32, of Tile Hill, Coventry, said: "It's a pathetic stunt. Leicester can't and won't beat us on the pitch. They are just clutching at straws."
However, Arron Ogilvie, 28, of Binley, Coventry, said: "It's a waste of the price of a Leicester top if you ask me.
"Coventry are perfectly capable of bringing about their own bad luck without the need for that."
A Coventry City FC spokeswoman insisted the club was not getting shirty about the attempt to jinx the ground - and had no plans to dig up the buried top.
She said: "We're delighted that Leicester City fans feel sufficiently threatened by the Sky Blues to try to curse us.
"As long as we're burying it in the back of the net, we're not too concerned!"