The Group A fixture is due to finish around 9:30pm and the last train departing London’s Paddington station for South Wales is 10pm.
The services leaving after 10pm are only due to go as far as Bristol.
Great Western Railway (GWR) has advised those trying to get back to Wales to make other travel plans or stay overnight in London.
The potential disruption is the latest in a series of complaints about the travel situation throughout England and Wales during the first week of the World Cup.