Daredevils from around the world are heading to the Spanish town of Pamplona for an alcohol-soaked fiesta and the thrill of being chased or trampled by charging fighting bulls.
Spain's most famous bull-run fiesta launches at noon on Friday with a shout from the City Hall balcony of "Viva San Fermin!" and the launching of a firecracker known as the "chupinazo".
Foreigners and locals alike, in traditional white garb with red kerchiefs around their necks, then spray anyone around them with wine as they sing and dance in the Plaza Consistorial.
The San Fermin festival, which dates back to medieval times, features religious processions, folk dancing, concerts and lots and lots of drinking; gallons of beer, wine and sangria.
But the highlight is a bracing, daily test of courage against a thundering pack of half-tonne, sharp-horned bulls - a spectacle immortalised by Ernest Hemingway in his 1926 novel "The Sun Also Rises".
Each day at 8am hundreds of people race along with six fighting bulls, charging along an 850-metre course from a holding pen to the northern Spanish city's bull ring.
The bravest or most foolhardy run as close as possible to the tips of the horns, preferably without being gored.
The first bull run, which traditionally draws the largest number of participants, is on Saturday.
This year though, the recession means the Pamplona tourist trade, too, is at risk of injury.
Pamplona Mayor Enrique Maya predicts about half a million people will flock to the city of 200 000 residents over the nine days, roughly the same as turned out last year.
But the Navarra Hospitality Association for the region of which Pamplona is capital is less optimistic.
It predicts hotel occupancy in Pamplona will be down by about 10 percent during the festival over last year because of Spain's recession, which has pushed the unemployment rate to 24.4 percent.
"Hotels are sold out for the opening weekend but after that the occupancy rate drops off to around 70 percent," said the association's secretary general, Nacho Calvo.
Visitors to San Fermin festival are also saving cash by staying for fewer nights, he said.
Pamplona city authorities will allow bars in the city to remain open until 6am during the festivities, which wrap up on 14 July.
It is banking on the festival bringing in more than €70-million in tourism earnings this year.
The bull runs are thought to have started when butchers began running ahead of the beasts they were bringing from the countryside to the San Fermin festival.
Dozens of participants are injured each year. Most of the injuries are not caused by bull horns but by runners falling, getting knocked over or run over by the animals.
The most recent death took place three years ago when a bull gored a 27-year-old Spaniard in the neck, heart and lungs with its horns.
Last year 20 500 people took part in the eight bull runs of the festival, the majority of them men between the ages of 18 and 35, according to Pamplona city hall.
Nearly half of all participants came from abroad with the United States, Australia and Britain accounting for the greatest number of foreigners.