Thirsty pub-goers have been urged to "be calm, be sensible" as boozers prepare to open their doors this weekend for the first time since March.
Met Police's Dame Cressida Dick, England's most senior police officer, issued the warning ahead of the re-opening day on Saturday.
She said the force had been preparing "for some time" and had "extra resources in place".
Dame Cressida told BBC Radio 4's Today programme: "My message is, if you're coming out on Saturday, be calm, be sensible.
"Look after yourself, look after your family. We are still in a global pandemic which is affecting this country very obviously."
Pubs were slam shut in March as the nation was placed under lockdown to contain the spread of coronavirus.
But Prime Minister Boris Johnson announced last month that pubs, restaurants and hairdressers could re-open on July 1.
They must adhere to guidelines including the new one metre "plus" rule, dropped from two if that distance is not possible.
Dame Cressida said she was "not predicting" violence but that the force has "more (officers) read should people get violent".
Yesterday a medic said staff were nervous about the re-opening.
Dr Katherine Henderson, the president of the College of Emergency Medicine, said: "We are nervous. We are bracing ourselves for this weekend.
"We do understand that people want to celebrate, but we’ve got to do this carefully. It is slightly scary for the NHS."
It was also reported that NHS officials had emailed hospital trusts to warn them of a weekend as chaotic as New Year's Eve.
It reportedly told them to "ensure that your demand/activity planning reflects a busy weekend, with peaks in activity into the evenings similar to that of New Year’s Eve".