Some Cardiff taxi drivers could strike on one of the city's busiest days of the year in protest at Saturday's Welsh Defence League's rally in the city centre.
Unite Against Fascism have asked drivers to leave work and join its counter-demonstration on Saturday.
The Welsh Defence League say they are against Muslim extremists and the introduction of Sharia law in Britain.
South Wales Police have said plans are in place to prevent major disruption.
Wales play South Africa in a rugby test at the Millennium Stadium, the Stereophonics play Cardiff City Stadium and Glamorgan take on West Indies A at the Swalec Stadium on Saturday.
South Wales Police have said that the Welsh Defence League rally will take place in Cardiff at 1400 BST.
Assistant Chief Constable Nick Croft said: "The police have a responsibility to facilitate every person's right of expression and their right to demonstrate lawfully. South Wales Police maintains a strictly impartial position on any related issues and causes.
"It is also our role to safeguard the right of the general public to go about their normal business, and to ensure the demonstrations do not disrupt local business activities."
Robert Goddard of Unite Against Fascism, which is part of the counter-demonstration, said he did not expect any clashes between the two groups.
"We're not going to march and have a confrontation," he said. "What we want is a celebration of Cardiff's multicultural community.
"We want to show everybody from Cardiff that this is our city as well."
Mr Goddard said estimates of the number of Welsh Defence League protesters varied greatly.
He said: "There could be anywhere from a couple of hundred to a lot more. So far 70 to 80 drivers have said they won't be working.
"They don't want to be working for the moral perspective and there were concerns that they might be on the receiving end of racism."
Cardiff has some 950 taxi drivers. The strike is expected to run from 1000 BST on Saturday to 1000 BST on Sunday.
Mathab Khan, chairman of Cardiff Hackney Carriage Association, sympathises with the drivers but is urging them to work.
He said: "A lot of our members believe that they (the Welsh Defence League) should not be able to hold a demonstration in Cardiff because Cardiff is a very diverse, mixed community.
"If we are going to strike, we are giving the fascist group a gain, which we don't want to do."