London Underground boss, Phil Hufton, tells me the two sides are still talking at ACAS, so there is still a chance the strike action could be called off.
READ MORE: Line-by-line guide of the affected services
The confrontation came during the Mayor's monthly phone-in show on LBC 97.3 - thought to be only the second time the two men have spoken.
The dispute over ticket office closures was deadlocked tonight with millions of commuters almost certain to be caught in the crossfire.
London Underground says services will be affected from around 9:30pm on Tuesday 4 February.