Viewers were left in stitches after social media star KSI performed on stage with a viral music act on the fourth semi-finals of Britain's Got Talent.

Sergey Stepanov, also known as the Epic Sax Guy, is a Moldovan musician who went viral for his saxophone melody at Eurovision in 2010.

He brought his melody to Britain's Got Talent, and after achieving a spot in the semi-finals, performed in the live semi-final this evening (May 16).

After previously promising to perform alongside the sax player if he got through, KSI joined him during his act.

KSI performs with Epic Sax Guy on Britain's Got Talent

During his song, Stepanov invited KSI to come on stage with him to play the saxophone too.

He ripped off his outfit to reveal a golden costume, and began playing, jumping on the judges' table and then being carried around in the crowd.

Fans of the show loved the act, with one saying: "KSI and Epic Sax Guy performing together has just made my night."

Another wrote: "That was epic.

"Epic Sax Guy and KSI together, that was special.

"As a huge fan of JJ's since the start, that was a brilliant moment."

A third said: "KSI performing with the Epic Sax Guy was absolute TV gold."

Epic Sax Guy was one of eight acts that took part in tonight's show (May 16), and finished fifth.

The other acts that performed were:

  • Wei Yamin - music/pyrotechnics act
  • Welsch Master Team - gymnastics team
  • Ren DMC - singer
  • Glantaf Boys Choir - a choir group from Wales
  • Sonny Green - poet
  • Rafferty Coope - magician and KSI's golden buzzer during the audition stages
  • Epic Sax Guy - musician
  • Kristel Herrera - singer

Poet Sonny Green was given the golden buzzer after his emotional performance left the judges and audience feeling emotional.

His poem was about his relationship with his sons and left KSI in tears.

Young magician Rafferty Coope won the semi-final this evening and secured his spot in the final later this month after getting the most votes from the public.

Who is in the BGT 2026 final so far?

There have been three semi-finals now for BGT 2026, with six acts confirmed to be in this year's live final on May 30.

  • Matty Juniosa - singer - golden buzzer in semi-final one
  • Anastasiia and Salsa - dog act - winner of semi-final one
  • LMA - dance group - golden buzzer in semi-final two
  • Fabian Fox - magician - winner in semi-final two
  • Liwei Yang - fire-juggler - golden buzzer in semi-final three
  • Ted Hill - comedian - winner in semi-final three
  • Rafferty Coope - magician - winner in semi-final four
  • Sonny Green - poet - golden buzzer in semi-final four

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What does the winner of BGT 2026 get?

There have been 18 winners of BGT since its first series in 2007, with magician Harry Moulding winning last year.

The winner of BGT will take home a prize of £250,000 and will also be given the chance to perform at the Royal Variety Performance in front of the royal family.

In the ITV show's first three years, winners won a prize of £100,000, while the biggest winners were Ashleigh and Pudsey with a prize pot of £500,000 in 2012.

Who is your favourite past BGT winner? Let us know in the comments below.