Umar Farooq is ESPNcricinfo's Pakistan correspondent
Karachi is being discussed as an alternative venue for England's historic first Test in Pakistan, as part of a back-up itinerary the PCB and ECB have been discussing as political unrest continues in Rawalpindi, the original venue for the series opener.
In this itinerary, the dates of the tour remain the same but Karachi hosts both the first and third Tests, with Multan staging the second as in the original schedule. England have not played a Test in Karachi for more than 20 years, since their famous twilight win in the 2000-01 series.
A final decision is expected to be taken in the next 48-72 hours, with the PCB keen to ensure all state and local bodies are on board with the switch.
Rawalpindi, home to army headquarters and next to the capital Islamabad, was due to host the Test from December 1. But unrest around the capital following the assassination attempt on former premier (and former captain) Imran Khan at a rally nearly two weeks ago has resulted in a series of protests since.
Khan escaped with injuries to his right leg and is now planning, with his PTI (Pakistan Tehreek-e-Insaaf - Movement for Justice) party, a long march on to the capital, demanding fresh elections.
He was ousted from power in April after a parliamentary vote of no confidence. Though no dates have yet been announced, the march from Lahore is expected to culminate in the capital towards the last week of November, around the time the England squad land.
Amid the public protest last week, the Quaid-e-Azam trophy game between Sindh and Khyber Pakhtunkhwa at Pindi stadium was first delayed for a day with the teams unable travel from the hotel to the stadium, then abandoned outright, with both teams taking five points. The latest round of the competition, which got underway on November 14, features ongoing matches in Karachi, Lahore and Abbottabad, with Rawalpindi not scheduled to host any further games.
ESPNcricinfo understands that the England tour isn't facing any direct threat from the ongoing situation, with the security of the team the PCB's highest priority, and the ECB on board with all the back-up plans. Last week, Ben Stokes, England's Test captain, said that his team would put its faith in the ECB's security delegation, led by their veteran advisor Reg Dickason.
Aside from the venue switch, the dates of the tour remain unchanged, with England expected to arrive from their training camp in Dubai on November 26-27, with the first Test set to begin on December 1. The second Test in Multan from December 9-13 and the third Test, already scheduled for Karachi from December 17-21, remain as originally planned.