The PSNI has said that anger and frustration around a flashpoint parade in Northern Ireland should not be allowed to explode into violence.
Orangemen celebrating the 12 July holiday will walk past Ardoyne shop fronts in north Belfast tomorrow night.
There are three other protests and demonstrations by loyalists and nationalists planned within hours of each other in the same inner city area where republicans and loyalists live.
Last year police officers fired baton rounds and used water cannon during hours of riots at the sectarian impasse during the culmination of the loyal order marching season.
This year Orangemen have been ordered to march past by 4pm and police have vowed to rigorously enforce the ruling.
PSNI assistant chief constable Will Kerr said that "listening to the groups over the course of the last week there is a lot of anger and frustration."
He said that there was "a lot of concern being voiced by both communities about various elements of the Parades Commission determinations."
He appealed for civic leaders to ask for calm and said he did not want to visit injured officers in hospital.
The Parades Commission, which rules on contentious parades, has decreed that Orangemen return from their main demonstration by 4pm tomorrow.
There is a republican march planned at 5.30pm in the same area.
Mr Kerr said they would uphold the Commission's determinations on the two parades.
Last year there was serious violence in the area.
Mr Kerr said: "There is no such thing as an inevitability of violence tomorrow."
He said the cycle of violence for two or three days a year threatened to undermine massively good work done during the rest of the year.
Mr Kerr pointed to the improvement in overall crime levels, at a 14-year low, and Northern Ireland's efforts to attract more tourists.
He said trouble could mean less jobs and that was not what any community wanted.
He said police had adequate resources to deal with trouble from wherever it came and said he could not see any circumstances where Chief Constable Matt Baggott would override the Commission's determination.
Parading last year cost the police service £5.7m.
There were 59 arrests in July in the Ardoyne area.
"Police officers will do their duty as required by the law. So should everyone else. The right to parade or to protest against a parade should not be used as an opportunity for violent and sectarian confrontation," he said.
Meanwhile, Northern Ireland Secretary Owen Paterson said enormous advances had been taken in securing jobs in Northern Ireland and also appealed for calm tomorrow.
Stormont Justice Minister David Ford called on politicians and community leaders to continue to use their influence for a trouble-free day.
The Orange Order holds its main Belfast demonstration, which commemorates King William III's 1690 Battle of the Boyne victory over Catholic King James II, at Barnett's Demesne, five miles away from Ardoyne.