A polished group performance from the X Factor-originating band was let down by some poor solos.
The quartet were great together as they rattled through their repertoire of pop covers including Coldplay's Yellow, Britney Spears' Oops I Did It Again and Christina Aguilera's Beautiful.
Their rendition of the Liverpool FC anthem You'll Never Walk Alone was genuinely hairs-on-the-back-of-your-neck time.
When it became time for one of the group to sing solo, though, each sounded flat, off-key and rather embarrassing.
Jon struggled to sing as he went walkabout among the crowd and Mike's serenading of a girl - apparently pulled from the audience - was excruciating.
Nessun Dorma, the overplayed opera classic, was extremely well performed and crowd-pleasingl. Sinatra tune My Way went down a storm.
The announcement that their record label, EMI, is to give G4 a third album and another chance to spread this particular brand of popera and hyped-up choir boy rock was met with universal approval by the Brighton Centre audience.
Hopefully, there won't be too many solos on it.
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