DOHA, Qatar -- The smart riyals are on U.N. climate talks here ending Saturday morning. But most diplomats said they booked flights for Sunday -- just in case.

The chaotic and ever-contentious two-week climate negotiations held each year in a different country have never, in the memory of many here, ended at 6 p.m. the final Friday as they are supposed to.

But with ministers haggling later into the night at each of the past several conferences -- culminating in a record-shattering 36 hours of overtime last year in Durban, South Africa -- veterans say they fear uber-extended negotiations will become the new normal.

"The last night and day has become the last night and day and night and day," said Doug Boucher, director of climate research and analysis at the Union of Concerned Scientists.

"By the time we get to 2013, it's probably going to be a three-week marathon," said Jake Schmidt of the Natural Resources Defense Council.

This year, the fight is bitter but not spectacular. A new global climate agreement may be delivered by 2015, and before that happens, developing countries want to ensure a few things: a steady stream of funding to help them build resilience to weather disasters, a way to steer countries into beefing up their emissions reduction targets before 2020, and a new phase of the still-sputtering Kyoto Protocol to bind a handful of nations to carbon targets over the next five years.

At a stocktaking session led by the president of the 18th Conference of the Parties -- or COP18 as it is known here -- Minister Abdullah bin Hamad Al-Attiyah said he has convened an informal meeting tomorrow morning to report on how countries are wrapping up.

"The real end is tomorrow," he warned.

The comment brought light laughter throughout the plenary hall. Asked whether she believes countries will really hammer out their differences on time this year, E.U. Commissioner for Climate Action Connie Hedegaard shrugged.

"You know how it is," she said. But Hedegaard said she thinks the thorniest issue -- agreeing on a funding commitment for poor and vulnerable countries -- has been helped by billions of dollars in pledges from the United Kingdom, Germany, Denmark, Sweden and France.

"They are starting to see on our side there is a will and a real commitment," Hedegaard said. "We are serious about coming up with the money."

Alf Wills, South Africa's lead negotiator, said he's betting on ending "Saturday sometime."

UCS's director of strategy and policy, Alden Meyer, said the only given is that no one is going home Friday night.

"Given the state of play, they would have to wrap up a lot of work tonight to have a chance of getting out of here tomorrow," Meyer said.

Besides, he added, "there's almost a negotiating culture that says if you end on time, you're not bargaining hard enough."