• Watch Martin Benn make three types of sushi

Bad news for Sydney, great news for Melbourne. The key players behind three-hatted Sepia – the highest-scoring restaurant in the latest Sydney Morning Herald Good Food Guide – are upping stumps and moving to Melbourne.

Chef Martin Benn and front-of-house manager Vicki Wild have teamed up with influential Melbourne restaurateur Chris Lucas, of Chin Chin fame, to find a significant CBD grid site for the restaurant they hope to open next year.

With the lease on their downtown Sydney restaurant coming to an end in 2018 and Sepia business partner George Costi retiring, Benn and Wild say the time was right for them to reinvent the Japanese-influenced restaurant – and shake up the Australian dining scene.

"We've been doing this for eight years," says Wild. "We've achieved far more than we thought we would in that time and it's really time to do something different and step it up a bit. But it's not about Melbourne. It's about Australia."

Sepia was ranked 84 in the 2015 World's 50 Best Restaurants awards, which also named Sepia the One to Watch. (Despite the name, the annual awards list the world's top 100 restaurants, chosen by an international jury of chefs, restaurateurs and food critics.)

When word went out that they would not renew their Sussex Street lease when it ends next year, the pair knocked back several offers from overseas before collaborating with Lucas, whose Lucas Group also runs Korean-Japanese restaurant Kong, pizzeria Baby and Singaporean street food restaurant Hawker Hall, and is weeks from opening an ambitious three-storey Japanese restaurant in Flinders Lane.

Lucas rates Benn as one of the world's best chefs. "He's more of a chef's chef. He's not a celebrity chef. He doesn't chase the limelight. But in my view he cooks some of the best food in the world."

They're unashamedly gunning for a restaurant of international acclaim. But don't expect it to simply be Sepia South.

"After we've finished here in Sydney we're going to have time to really work through and create something very different," says Wild. "I don't see the point of doing what we're doing now and just dropping it in Melbourne. If anything we'll be stepping it up, not stepping it down."

Meanwhile, Benn and Wild are amping up Sepia for the final stretch, before turning off the lights for the last time on December 31 .

"This announcement gives our staff, who are like family, clarity for the future," says Wild. "Our loyal guests and friends can be assured we will be giving it our all over the remainder of the year at Sepia. We won't be winding down, we will be dialling it up and going out with a bang."