No-nonsense classic cocktails, such as the gin and tonic, old fashioned, negroni and highball, are getting updates at four bars that want to capture their essence while challenging traditional representations of them.

They do this by using different flavour profiles and garnishes and interpreting the classics in new ways.

The Flagship in Bukit Pasoh road calls itself the home of the boozy, spirit-forward old fashioned, using its extensive collection of more than 200 whiskies.

Garden gin bar The Rabbit Hole, on the other hand, celebrates gins and has a housemade tonic.

The negroni was chosen to be highlighted at Potato Head Folk because of its complexity of flavours. "It's a simple drink, but it's hard to get right," says Mr Kamil Foltan, group development bar manager at Potato Head.

Over at newly opened Highball, the cocktail of the same name - made with a base spirit, soda water and lots of ice - is the hero, with more than 40 variations.

For head bartender Kino Soh, it is about going back to the fundamentals of a good drink.

"When I started drinking, I liked dessert-like cocktails. Then when I got into bartending, I preferred complex and bitter drinks," she says.

"But I love the simplicity of the highball cocktail. And your palate goes back to basics."

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Highball cocktails at Highball

Where: 79 Kampong Bahru, 01-01

Open: 4pm to midnight (Mondays to Saturdays), closed on Sundays

While the term highball may conjure up images of Japanese salarymen downing whisky highballs packed full of ice and soda, head bartender Kino Soh's establishment serves the cocktail with all varieties of spirits - rum, gin, shochu or sake.

The bar, helmed by an all-woman team of bartenders, is just a little over two months old.

Ms Soh, 29, feels that given the tropical weather in Singapore, the light and refreshing cocktail is a great fit for the climate.

There are more than 40 varieties of highballs grouped according to the base spirit in an easy-to-navigate menu. Served in smaller glasses, they are priced from $10 nett.

Bestsellers include the Kyoho Fizz ($15, made with Tanqueray gin, Kyoho grape liqueur, lemon juice, soda and garnished with sour plum) and the fizzy, thirst-quenching Jim Beam yuzu citrus highball ($10), made with bourbon soda from an in-house draft tap.

Ms Soh started to appreciate highball cocktails while on an internship in Tokyo's Bar High Five, headed by master mixologist Hidetsugu Ueno. She ordered a highball with every meal to see how it fit into the lifestyle of the Japanese and was inspired to bring that culture here.

"These days, people are going for lighter drinks. That means you can drink more at one go," she says.

Old fashioned at Flagship

Where: 18/20 Bukit Pasoh Road

Open: 6pm to 1am (Mondays to Thursdays), 6pm to 2am (Fridays and Saturdays), closed on Sundays

The old fashioned has been made the same way for more than 100 years - with a whisky base, bitters, sugar and citrus rind.

But at Flagship, you can have the classic, a signature version or customise your own. The bar stocks more than 200 whiskies from all over the world - from the standard Speyside Scotch to an Indian single malt such as the Amrut.

"The old fashioned cocktail has become a gateway to exploring whiskies," says Mr Indra Kantono, co-founder of the Jigger & Pony family of bars.

"A lot of bars don't pay attention to it because it's deceptively simple, but there're a lot of ways you can twist an old fashioned."

Instead of a long list of options, there are four takes, at $22 each, created by principal bartender Jerrold Khoo. They include the classic version, which uses rye-heavy Bulleit bourbon with Angostura bitters, dark sugar and an orange twist.

Another, called Wine of the South, is a softer approach meant for entry-level drinkers, using black tea, peach bitters and Michter's small batch bourbon.

Ultimately, the bar wants the experience to remain accessible.

"I hope purists and whisky connoisseurs will relax a bit when they come here," says Mr Kantono. "But for new customers, we want it to be friendly and exciting."

Gin and tonic at The Rabbit Hole

Where: 39C Harding Road

Open: 6 to 11.30pm (Tuesdays to Thursdays, Sundays), 6pm to 12.30am (Fridays and Saturdays), closed on Mondays

In a lush garden setting just behind The White Rabbit restaurant is a gin bar with a curated selection of craft gins that serve as the base for summery gin and tonic cocktails. Served in large copa - or goldfish bowl-style glasses - with generous 40ml pours, they cost $17 to $22.

The Rabbit Hole's list of 20 craft gins are grouped according to the style they represent.

Mr Joshua Baxter, 32, group beverage manager at The Lo & Behold Group, finds that this helps customers navigate what is on offer. "If people come in and don't understand gin much, it puts them in a frame of mind and helps them make a better choice for their personality."

For instance, under the "simple and honest" section, you find smooth gins that are less tart, such as Plymouth gin or Death's Door gin, while under the "complex and unexpected" section, you find German gin Monkey 47, which is made with 47 botanicals.

The menu also includes what garnish and tonic would go best with the gin. The Monkey 47 gin and tonic, for instance, is made with East Imperial Burma tonic and garnished with a lemongrass stalk and lime wheel.

High-quality tonics, such as Fever-Tree, East Imperial and the soon-to-be-introduced Erasmus Bond, are used alongside a tonic made in house with orange, lime, lemon and grapefruit. Five more gins are to be added next year.

The bar also organises gin workshops on the spirit's history, giving customers hands-on experience in making gin martinis and coming up with their interpretations of gin and tonic.

The next workshop will be held in the first quarter of next year.

Negroni at Studio 1939, Potato Head Folk

Where: 36 Keong Saik Road

Open: 5pm to midnight (Tuesdays to Sundays), closed on Mondays

The negroni is king at Studio 1939, located on the third floor of Potato Head Folk.

A classic negroni is typically made with equal parts sweet vermouth, gin and Campari (the bitter Italian liqueur) and garnished with an orange twist. But every Tuesday night, the bar hosts a Negroni Lab from 5 to 9pm, where five negroni variations ($24 to $26) are on offer. For every glass ordered, you get one free.

Takes on the classic include unexpected ones such as coconut negroni ($24), made with Mahiki coconut-infused rum, sweet vermouth and Campari. The mellow and fruity variation has a sweet start and a bitter end. There is also coffee negroni ($24), made with Tanqueray gin, coffee-infused vermouth and Campari.

Mr Kamil Foltan, 31, group development bar manager at Potato Head, acknowledges that these are two cocktails that people do not expect to work.

"But it's great to see their surprised faces once they sip the drink," he adds.

The five negronis are available during the rest of the week as well, but at $20 each. For $120, you could also get a bottle of 30-day barrel-aged negroni that serves 10.