Talks aimed at resolving the London Underground dispute will be held tomorrow, but a crippling strike will continue today.
Tube services are being disrupted because of a walkout by members of the RMT and TSSA unions in protest at the closure of ticket offices.
The 48-hour walkout will end at 9pm tonight, with another strike planned for next week unless the deadlock is broken.
The unions have been calling on London Mayor Boris Johnson to meet them to discuss the controversial closures, with the loss of 950 jobs.
The mayor has refused to meet the unions unless they called off the industrial action.
The conciliation service Acas said in a brief statement: "The parties in the London Underground dispute have agreed to come in and continue exploratory talks at Acas this Friday, February 7."
RMT leader Bob Crow said last night: "Our negotiators are geared up and ready to enter the exploratory talks on Friday.
"In the meantime the current action continues with the rock solid support of our members and we will be back out on the picket lines early tomorrow morning as the strike heads into its third day."
LU managing director, Mike Brown said last night: "We welcome further talks, and the unions' decision to return to Acas, but why wait till Friday?
"I call on the leaderships of the RMT and TSSA to meet us tomorrow and to suspend Thursday's strike so we can get on with talks to resolve this issue and avoid any more unnecessary disruption to Londoners."