As coronavirus restrictions were eased, the streets of Leicester remained deserted due to the local lockdown. But police said they faced a "huge challenge" as pubs outside the lockdown zone opened, with officers called to a number of incidents.
Leicestershire Police Chief Constable Simon Cole said there was "huge compliance" within the lockdown boundary as people adhered to guidance by staying at home on Saturday.
"Sadly, there were however a number of incidents last night too," he said.
Mr Cole said it had been challenging policing two different sets of rules.
Pubs in the county opened for the first time since March while officers patrolled the city to enforce the local lockdown.
More officers were on duty than a typical New Year's Eve.
A dispersal order was put in place in Market Harborough on Saturday night after reports of anti-social behaviour.
A pub in Narborough was forced to close early after a 35-year-old man was arrested on suspicion of affray.
Police said the victim sustained injuries to his neck and was taken to hospital with injuries not believed to be serious.
Officers in Blaby, who dispersed a house party in locked-down South Wigston, described the night as a "challenging shift for all officers".
👮♀️WHAT A SHIFT !!👮♂️— Blaby Police (@BlabyPolice) July 5, 2020
PC Jodie & PC Stu were crewed up as part of the Forcewide Op, involving licensed premises, groups & ASB.
🟦We haven't stopped all night, with other officers who have also done long hours today (longer than us!). We have finally booked off after 13.5 hours🟦 pic.twitter.com/pF84zDTuCl
Pubs outside of the lockdown zone asked customers for identification to check they had not travelled from within the restricted area.
Matt Naylor, 29, who was a customer at the Coach and Horses in Anstey, said: "Everyone is drinking together for the first time, but everyone is respecting the pub's one-way system.
"Some people have been idiots. The pub's ID'ing everyone, so they're doing the right checks and making sure nobody is coming in from the lockdown area."
Well behaved happy pubgoers in Anstey this evening. A handful of people turned away trying to sneak in from areas where they shouldn't be leaving (please be aware pubs are completing photo ID checks) but all in all a good night had. Thank you, PC 330 Greg Moore #TeamAnstey pic.twitter.com/me6oIBt2t6— Charnwood Police (@CharnwoodPolice) July 4, 2020
Mr Cole said: "This time has been a huge challenge for all of us.
"We are effectively policing a force area where different government guidelines apply to different areas.
"But the way that my officers and staff have responded to this has simply been outstanding."
He added he was "proud of the dedication and commitment" from everyone involved and thanked the vast majority for adhering to the guidelines.
Leicester and some suburbs became subject to the UK's first local lockdown on Monday.
The Leicestershire areas included are Braunstone Town, Glenfield, Glen Parva, Leicester Forest East (east of the M1), Thorpe Astley, Birstall, Thurmaston, Oadby and Wigston.
A postcode checker has been set up by Leicestershire County Council that allows people to see if their area falls inside or outside the lockdown boundary.