The group, who shot to fame as runners-up in reality TV talent show The X-Factor three years ago, performed at the popular venue in one of their last appearances before they split this autumn
So it was a farewell of sorts to the home crowd of former Cambridge schoolboy Ben Thapa, who makes up the foursome with Jonathan Ansell, Matt Stiff and Mike Christie.
The concert was part of a final summer tour for G4, who are expected to go their separate ways in September, which will top the spectacular success enjoyed by the group since they won X-Factor judge Simon Cowell's approval in 2004.
Ben, who went to Parkside Community College in Cambridge, said: "It has been so important for us to do this tour, because our fans have been amazing. They are so dedicated they would come to the opening of a shoebox for us.
"We owed it to them to put on a really good show. Some people might think singing at the Albert Hall is cool, but playing Newmarket in July was an amazing opportunity for us too."
Despite speculation about why G4 are splitting, 25-year-old Ben insists they "just wanted to go out at the top."
He said: "We all sat around talking about the future, and we just realised that we had four different horizons which did not involve each other."
But opera fans should fear not - Ben is also adamant that his career as a classical musician is only just beginning.
He said: "I've got a classical agent, and I'm just planning to get involved in more classical singing and, hopefully, one day get on the opera stage."
Among the other famous groups to have wowed the crowds in Newmarket this summer are Australia rockers INXS and girl group the Sugababes.
Source: Cambridge Evening News