Pakistan is preparing for a spate of religiously-motivated violence during the next 24 hours, introducing security measures that include the suspension of mobile phone services.
The Shia Muslim procession of Chehlum takes place on Tuesday, marking the 40th day after Ashura and the martyrdom of Imam Hussain.
Commemorations in previous years have seen dozens of people killed and hundreds more injured.
As Christmas gets nearer I miss them more and more. I miss them as much as it is possible to miss anyone.
This year Pakistani newspapers are widely reporting that 10,000 police officers will be on duty in Karachi alone, with a further 5,000 in Quetta, as intelligence reports suggest that armed groups will once again target processions and the law enforcement officials protecting them.
To further reduce the possibility of bloodshed Pakistani authorities are also closing schools, markets and banning pillion riding in some areas.
The Pakistan Telecommunications Authority has ordered the temporary closure of mobile phone networks in 31 cities.
Church bombing haunts Christians
In Peshawar preparations of a different kind are under way, as Christians in the city contemplate their first Christmas since a devastating attack on the congregation.
Eighty-two people were killed when a double suicide attack targeted their place of worship three months ago.
The incident at All Saints church is believed to be the deadliest ever against Muslim-majority Pakistan's small Christian community.
"As Christmas gets nearer I miss them more and more. I miss them as much as it is possible to miss anyone," Anwar Khokar told AFP news agency on Sunday.
The 53-year-old lost six members of his family in the attack, including three brothers.
"I miss our relatives so sadly, one of my brothers especially. It's so hard that he's not with us this Sunday and especially at Christmas."
Security at the church has improved since the attacks, with extra guards manning the gateway through the thick blast walls and barbed wire.
A fingerprint-scan entry system has been installed but is not yet operational.