Fans travelling from London to Saturday's FA Cup third round tie with Portsmouth by rail face delays with a bus service replacing trains on part of the journey.
The service from London is also expected to be very busy with Portsmouth fans making their way to Portman Road and West Ham supporters off to Carrow Road for their match with Norwich City.
British Transport Police will have a strong presence on both the trains and buses. A spokesman for the BTP says they wanted one of the matches moved: "There were a number of games we asked about and the authorities changed some of them but they ran out of options in the end.
"We did express concern over these fixtures. This isn't ideal but we have got an operation planned. There will be travelling officers on all the trains and buses.
"We are not anticipating any major problems, but it is a concern."
More details on the rail disruption here.