Police chiefs are warning that 'the vast majority' of Sheffield city centre is covered in CCTV cameras - in a bid to deter people from violence on nights out.
South Yorkshire Police issued the warning in the wake of two incidents in Carver Street.
In one, Billy Gilberthorpe, aged 21, of Ecclesfield, was attacked by a man carrying two miniature glass bottles moments after walking into Crystal in the early hours of Sunday.
The chef and machine operative said his attacker ran at him from inside the bar and smashed two bottles over his head.
He was left with wounds to his face and the back of his head, with two of the cuts just an inch away from one of his eyes.
Officers are also investigating an incident 24 hours earlier at Beg, Borrow and Steal, on the same street.
Enquiries are underway into how 23-year-old Grant Foster suffered a wound from his ear and down his neck.
Inspector Matt Collings, of South Yorkshire Police, said: “I understand there have been two incidents recently that may have caused concern and I would like to offer my reassurance that this type of crime is not tolerated.
"Both of the incidents are being fully investigated by officers and we will work hard to bring those responsible to justice.
"Those wishing to engage in such activity should be warned that the vast majority of the city centre is covered by CCTV and we will pursue relentlessly those who would seek to harm others.
“Keeping members of our community safe within the local night time economy is a priority for us. We have dedicated high visibility patrols during the busiest times and we work closely with our partner agencies to try and create an environment that is both enjoyable and safe for those wishing to come into the city.
"We also always review such incidents with any licensed premises involved to see if we can prevent future occurrences or make them less likely to occur.
We also carry out regular dedicated operations and have a number of campaigns, such as the forces latest knife crime campaign, to raise awareness and provide information on crime within the night time economy.”
Anyone with information should call South Yorkshire Police on 101.