Spaniards will wake up on Sunday to find that what many consider an inalienable right - puffing on a cigarette with a drink at their local bar - has overnight become illegal.
On January 2, one of the laxest anti-smoking laws in Europe will have become one of the strictest, along with that of Ireland.
Spanish smokers will no longer be able to light up in bars, restaurants and cafes as new legislation takes effect that bans smoking in all enclosed public spaces.
It will also be illegal to smoke in children's playgrounds and on school or hospital grounds, according to the law, which received final approval from parliament on December 21.
Spain already has an anti-smoking law, in force since January 2006. But it is less restrictive than that in other European countries, which bans smoking in the workplace, on public transport and in shops.
It allows owners of bars, restaurants and cafes to decide whether to allow smoking or not. Most, faced with a drop in business, naturally chose to permit their customers to light up.
The new measures take effect nearly seven years after Ireland became the first European country to outlaw smoking in public places, a move that unleashed a domino effect across Europe in favour of smoke-free bars and cafes.
But the new Spanish law has many professionals in the hospitality industry fuming.
The government has "imposed a total ban without regard to the figures that we have presented, or without an objective and rigorous study," said Jose Luis Guerra, vice president of the Spanish Hotel and Catering Association (FEHR).
He said bars and restaurants "have been very badly hit by the economic crisis," suffering "31 months of falling sales."
He estimates the ban could spark a further 5.0-percent drop in sales in restaurants, about 10 percent in bars and 15 percent in night clubs - just as the country is struggling to emerge from the crisis.
His association has proposed a system similar to that in France, where separate smoking areas with ventilators are permitted, he said.
Dominic Brisby, the chairman of Spanish tobacco company Altadis, a unit of Britain's Imperial Tobacco, called it "one of the most radical anti-smoking laws in the world."
"It is even more extreme than in Ireland, as there they can smoke outdoors, and here it is prohibited in some situations," he told Spain's leading daily El Pais.
"It seeks to turn those who smoke in bars into second-class citizens, and it will fail because it will cause enormous economic damage, for those who smoke and for those who don't."
One smoker, Ignacio, a 42-year-old soldier who was puffing away in the crowded bar in Madrid, condemned it as "a backward step, especially considering the lifestyle here we have here in Spain, the social life in places like this."
Health Minister Leire Pajin has backed the law as "a decisive step in the defence of the health of the Spanish people."
She said it could even be a boon for bars and restaurants as it would encourage non-smokers, especially those with families, to go out more. But she acknowledged it would "demand changes" which would "take time" as "habits cannot be changed in a day."
And some in the industry even agree.
"It will obviously hurt us financially," said Alfonso Castro, co-owner of El Borbollon restaurant in central Madrid.
"But in a few months people will get used to it, as they did in Italy, Germany and England, and there won't be any problem."
A non-smoker himself, he said that 28 years working in a smoky environment had left him with problems with his blood circulation.
Mario Flores, the manager of the Monte Nevado restaurant in Madrid's Chueca nightlife district, agreed that small establishments such as his would not suffer as customers would quickly get used to the new restrictions, although night clubs would be hard hit.
The new law could even have one unforseen social benefit, according to an opinion piece in El Pais.
Once the law takes effect "we will be seeing new knots of people at doorways exchanging complaints, cigarettes and phone numbers..," it said.
"After the cigarette, new couples return to drinks or work, to further enjoy a conversation started around a lighter's spurt of flame."