Sunderland are reportedly aware of Newcastle's fans looking to take advantage of a £1 ticket offer for kids in order to mock their prospective relegation to League One.
But on Tuesday night, before the Black Cats' 1-1 draw with Norwich, the Championship strugglers subtly introduced a preventative measure. Home supporters were told to purchase tickets from the ticket office rather than at the gate, which also worked out £5 cheaper, to vet all fans entering the stadium.
Anyone buying tickets from the office had to prove they had a purchase history so could be checked.
Sunderland still have two Championship games to host against Burton and Wolves, and will continue to adopt the same policy so that Newcastle fans looking for a relegation party can't cause disruption.
In 1987, 1,000 Newcastle fans turned up to watch Sunderland get relegated to the third tier for the first time in their history when Gillingham knocked them out of a play-off second leg on away goals.
Last month, seats were smashed during a Sunderland vs Newcastle U23s match at the Stadium of Light, which looks to have been factored into the decision.
Even though Chris Coleman's side have picked up five points from their last four matches, the Wearside club currently sit 23rd in the second tier and are six points off safety with four games left to play.
Sunderland travel to the Madejski Stadium to face fellow strugglers Reading on Saturday.
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