London Underground maintenance and engineering workers are to stage a three-day strike over the weekend of the FA Cup Final later this month in a row over safety.
The Rail, Maritime and Transport (RMT) union said more than 1,000 of its members will walk out from 7am on May 17.
Tens of thousands of football fans will be travelling to Wembley on Saturday May 18 for the game between Manchester City and Watford.
The union claimed train preparation and inspection schedules were being “hacked back”.
The RMT said its members had voted by 9-1 in favour of industrial action.
RMT General Secretary Mick Cash said: “The ballot result showed just how angry Tube staff are at proposals London Underground are attempting to bulldoze through that would decimate the inspection and safety culture on the fleet.
“Despite that result Tube bosses have ignored the workforce and are pressing ahead and it is that intransigence that has left us no option but to confirm industrial action.
“Our message is clear, LU should pull back immediately rather than crash on regardless of the consequences of their actions.
“We remain available for genuine and serious talks.”
Workers involved in the dispute are based at maintenance depots across London. The union claimed that plans to “decimate” inspection frequencies would lead to more Tube train failures.
Peter McNaught, Director of Asset Operations for London Underground, said:
“We have plans in place to ensure we can deliver a Tube service for our customers, and keep disruption to a minimum.
“The safety of customers and staff is our top priority and our proposals do not compromise this. Train checks will continue daily, with every train thoroughly checked to guarantee safety.
“Our proposals are to change the frequencies of some less safety critical checks, with the regulator, the Office of Rail and Road, satisfied with our approach.
“We have actively consulted with the trade unions over this issue and we remain open for discussions on how to resolve this dispute without unnecessary industrial action.”