Take That fans were sent wild on the first night of Robbie Williams' Sandringham concerts as his former bandmate joined him on stage.

Mark Owen had already been announced as the special guest for both his Saturday and Sunday night shows, with his set from 7pm until 8pm.

However, on Saturday he reappeared later in the evening during Williams' set for a duet on the Take That song Greatest Day.

READ MORE: Robbie Williams, Sandringham review: The ultimate showman

Greatest Day was released in 2008 as the lead single on The Circus album and it reached number one in the charts. 

Eastern Daily Press: Mark Owen during his own set ahead of Robbie Williams' performances Picture: Lee Blanchflower (Blanc Creative)Mark Owen during his own set ahead of Robbie Williams' performances Picture: Lee Blanchflower (Blanc Creative) (Image: Lee Blanchflower (Blanc Creative))

After wearing a green boiler suit for his own set, Owen changed into a black shirt and wide-leg red trousers for his duet.

READ MORE: Robbie Williams' Sandringham concerts: Setlist confirmed

Fans took to social media after the concert to share their joy at the mini Take That reunion. 

Claire posted: "Mark Owen coming on stage and them hugging was so cute. Duet was amazing."

Robbie Williams performs his second concert at Sandringham on Sunday night, followed by The Who on Monday.