American burger joint Five Guys Singapore marked its launch at Plaza Singapura on Monday with about 100 people in line prior to the store's opening at 11am.
The first person started queuing from 4am, said a spokesman, and the average queue time that day was about one hour.
By 7pm on Monday, more than 1,000 burgers and 500 milkshakes had been sold.
The brand prides itself on its hand-cut fries cooked in peanut oil, as well as its burger patties with an 80-20 lean meat-to-fat ratio.
Its burger buns - made with Five Guys' recipe - are freshly baked five days a week at a local bakery.
Patrons must order burgers, fries (original or with Cajun spices, from $7) and drinks (from $4 for a bottle of water) separately as there are no set meals.
Prices start at $11 for a single patty Little Hamburger, and at $10 for a hot dog.
The burgers and hot dogs can be customised at no extra cost.
Just select your favourite toppings or go "all the way" to have everything included in your burger or hot dog.
Toppings include grilled onions, grilled mushrooms and pickles.
Similarly, the Five Guys Shake ($10) can be customised.
Mix in anything from chocolate to salted caramel and banana, and even bacon bits - all at no extra cost.
The 460 sq m space seats 52 diners indoors and will eventually include outdoor seating as well.
Five Guys was founded in Arlington, Virginia, in 1986, by the Murrell family and named after their five sons.
It was run as a family business until 2003, when they went into franchising.
The Five Guys franchise - which has more than 1,600 restaurants worldwide across the United States, Europe, Middle East and Asia - is brought in by lifestyle company Zouk Group.
The opening of Five Guys in Singapore rounds up this year's notable burger news.
This includes the debut of New York's Shake Shack burger restaurant chain at Jewel Changi Airport in April.
Shake Shack recently announced the opening of another outlet in Neil Road next year.
Over in Duxton Road, Lombardo's Burger from Amsterdam made headlines in October for its "Most Expensive Burger in Singapore" at $250.
The over-the-top burger includes a 200g patty of seared Japanese Kobe wagyu brisket topped with a butter-poached lobster tail, pan-seared foie gras and a gold leaf-covered bun.
• Five Guys Singapore, 01-32 Plaza Singapura, 68 Orchard Road; open: 11am to 10pm daily. Go to www.facebook.com/FiveGuysSingapore