It does not take long for things to change drastically in this miserable petrol dispute.
Last Friday, I was standing outside Acas HQ at Euston when the union's chief negotiator Diana Holland emerged with a flourish to say they had reached a "joint proposal" after "constructive talks".
Putting this breakthrough to the union membership seemed a mere formality. Just a few days later and I was sitting at union HQ when Diana arrived to tell us the proposal was not nearly good enough - failing to give enough on terms and conditions.
The deal has been rejected by members and fresh talks are being sought.
It is a setback in the process aimed at preventing more scenes of panic and shortages. Haulage firms tonight called rejection of the proposals "a serious blow".
Geoff Dunning from the Road Haulage Association told ITV News he found it hard to understand how well-paid drivers should wish to continue the dispute.
Meanwhile, the Government said its preparations - using army tanker drivers - will continue, even while the union attempts to restart talks. Garage owners are telling me they are better prepared this time, having boosted stocks.
For millions of motorists caught up in a forecourt battle not of their making, Friday now emerges as a crucial deadline. Beyond that the union loses its ballot mandate for any action.
After a year of dispute and weeks of complex discussion it seems this dispute has come down to a 48-hour scramble.
So how should motorists respond?
The union say "don't panic" - there are (at this stage) no strike plans, no strike dates. They are stressing they are committed to fresh talks.
Even if no deal is done by Friday there are options: for example a token 15 minute walkout which would have the effect of extending the union's strike mandate.
Progress has been made on health, safety and training - agreement has been achieved. So where has all this come unstuck?
The union says they want more from bosses on "terms and conditions". It is clear bosses suspect that is a 'Trojan horse' for a national pay negotiation - something they say they will never allow.
So for now, no immediate cause for alarm, but keep watching and I will be discovering all I can in this crucial 48-hours. One thing we know about this dispute is that things can change very quickly (just ask Diana Holland).