LONDON — As far as Derry City was concerned, it was a big game. A cup quarterfinal, on home turf, against one of its fiercest rivals from the League of Ireland should have been the sort of night to draw a raucous crowd, the gate receipts swelling the club’s coffers.

As the game kicked off, though, the crowd at the Brandywell Stadium, Derry’s compact home, was far short of what Sean Barrett and his fellow directors had been hoping for. “It was really bad,” he said. Derry ordinarily draws a couple of thousand fans to home games; for that game against Bohemians, it was down by a quarter or so, he said.

He did not need long to work out why.

The same evening, Manchester United was taking its bow in the Champions League, beating Young Boys, the Swiss champion, 3-0, in Bern. The game was broadcast live in both Northern Ireland, where Derry is based, and Ireland, the home of Derry’s league.

United, like the other great English powerhouses, has vast numbers of fans in both countries, so many that the local teams simply cannot compete.