Tube drivers on the Piccadilly Line are due to begin a 52-hour strike in a row over working conditions and staffing.
Rail, Maritime and Transport workers' union (RMT) members will walk out from 21:00 BST until 01:00 on Saturday.
Talks are continuing at conciliation service ACAS but transport bosses have advised people to finish journeys on the line by 22:00 if the strike occurs.
The action is set to coincide with England's World Cup semi-final as well as Donald Trump's visit to the UK .
No service will run on the entire line including the Night Tube on Friday night during the strike, Transport for London (TfL) has said. It said it would mean services resuming at 07:30 BST on Saturday.
Interchange stations along the Piccadilly Line including Finsbury Park, Green Park, Hammersmith, and King's Cross St Pancras are expected to be particularly busy.
About half a million passengers travel on the Piccadilly Line each day, with the route linking central London to Heathrow Airport.
Up to 30,000 people are expected in Hyde Park , which is partly served by the line, for a screening of England's match against Croatia on Wednesday evening.
The match starts before the strike action is due to begin but the walkout could affect fans travelling home afterwards.
The RMT has said it is holding the action because of "repeated problems" including a shortage of drivers and an "ageing fleet".
Nigel Holness, TfL's director of network operations for London Underground, has called on the union "to work with us constructively on the local issues they have raised, so that Londoners aren't subjected to disruption".
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