Workers at two TGI Fridays sites will walk out in a 24-hour strike at 11am today in an escalation of a row over changes to the way tips are distributed.
Employees at restaurants in Milton Keynes and Covent Garden will strike over the changes, which union Unite claims could cost waiting staff as much as £250 a month.
Unite has said the move was met with opposition by front and back of house employees alike, with waiting staff angry about the loss of card tips and kitchen staff unhappy about swapping a rise in basic pay for a share of tips.
The move led to staff protests outside three of the 83-strong restaurant chain's London sites on the evening of Valentine's Day, with Unite saying the company has "refused" to enter discussions.
Unite regional officer Dave Turnbull said: "Unite is warning TGI Fridays of a summer of disruption if management don't do the decent thing and sit down with us to find a sensible solution to this dispute.
"Our members have sent a very clear message that they will not roll over and be bullied into having their tips taken, without any consultation and with just two days' notice - a move that will leave waiting staff up to £250 a month worse off.
"This isn't about minimum wage servers not wanting to share with their kitchen colleagues. It's about a company whose shareholders have gotten so greedy that they no longer want to pay their hardworking staff anything above the bare minimum."
Lunchtime protests will be held outside the two branches before London workers join a low pay rally with McDonald's workers.
A second strike affecting restaurants in London's Piccadilly and Manchester's Trafford Centre is planned for next Friday with ballots also taking place at branches in Enfield and Newcastle.
A TGI Fridays spokesman said: "Our team members are a part of our Fridays family, and we care about them. We believe all our team members should be - and are - treated and paid fairly. Despite this, a small number at Milton Keynes Stadium and Covent Garden have voted to strike. We are listening to them and are collectively working to find a resolution. In the meantime, we will be doing all we can to ensure our guests receive the usual great dining experience and that the restaurant remains open as normal."