Firms are being urged to accommodate requests from staff to watch their team play in the football World Cup.
The conciliation service Acas said employers should be flexible when allowing workers time off.
Businesses were advised to plan ahead, with just weeks before the tournament starts on Thursday, June 14 in Russia.
Kick off times will vary between 1pm and 8pm.
Acas chairman Sir Brendan Barber said: "The World Cup is an exciting event for many football fans but staff should avoid getting a red card for unreasonable demands or behaviour in the workplace during this period.
"Employers should have a set of simple workplace agreements in place before kick off to help ensure their businesses remain productive while keeping staff onside."