Three men have been arrested in connection with the stabbing of a 27-year-old outside Primark in the city centre at the weekend.
The suspects - two aged 19 and one aged 21 - were taken into custody this morning.
Police have also now released an image of the sweater the victim was wearing at the time of the attack, in an attempt to jog the memories of people who may have been around at the time.
It is a light grey sweatshirt, featuring an image on the front of a bearded man wearing a bobble hat.
The victim is of mixed race, around 5ft 10ins tall and of a muscular build. He has closely cropped, dark hair.
The incident happened at around 1.45am on Sunday November 11.
The victim was taken to the Queen's Medical Centre with critical injuries, but has shown signs of improvement over the last two days.
He is now in a stable condition.
Detective Inspector Keith Priest said: "The top worn by the victim that night made him quite distinctive. Did you see him?
"We believe the attack took place near the Brian Clough statue not long before the victim was found. We also think a number of people were involved.
"Were you out in the city that night? Did you see anything suspicious? Have you learned of anything since that night that you think might help us with our investigation?
"Officers will be handing out leaflets and speaking with revellers at the scene and at pubs and clubs in the city centre on Saturday night (November 17 2012) as part of an anniversary appeal for more information.
"If you saw the attack, or have any information, please call us or make yourself known to an officer. Any information you provide will be treated in the strictest confidence."
Anyone with any information is asked to contact Nottinghamshire Police on 101, quoting incident 119 on Sunday 11 November 2012, or call Crimestoppers anonymously on 0800 555 111.
