What you need to know:
- The shooting was the latest twist in months of political turmoil that began in April when Iman Khan was ousted
- The rally will take place on a vast open ground between the capital, Islamabad, and neighboring Rawalpindi
Islamabad. Former Pakistan prime minister Imran Khan is expected on Saturday to address thousands of supporters at his first public appearance since being shot earlier this month in an assassination attempt he blamed on his successor.
The shooting was the latest twist in months of political turmoil that began in April when Khan was ousted by a vote of no confidence in parliament.
Saturday's rally is the climax of a so-called "long march" by Khan's party, the Pakistan Tehreek-e-Insaf (PTI), to press the government to call a snap election before parliament's term expires in October next year.
"My life is in danger, and despite being injured I am going to Rawalpindi for the nation," PTI quoted Khan as saying in a morning tweet.
"My nation will come to Rawalpindi for me."
On Saturday, a video was circulating of aides posing with a now-removed blue cast that Khan wore on his right leg after the shooting.
The rally will take place on a vast open ground between the capital, Islamabad, and neighbouring Rawalpindi -- the garrison city that is home to the headquarters of the country's powerful military.
Authorities have thrown a ring of steel around Islamabad to prevent Khan's supporters from marching on government buildings, with thousands of security personnel deployed and roads blocked by shipping containers.
Khan-led protests in May spiralled into 24 hours of chaos, with the capital blockaded and running clashes across Pakistan between police and protesters.
Police said any attempt by PTI supporters to enter Islamabad this time would be firmly dealt with.
Interior Minister Rana Sanaullah -- who Khan says was involved in the assassination plot -- issued a "red alert" Friday warning of security threats to the rally.
"PTI still has the time (to cancel)," he said, listing Pakistan's Taliban and Al Qaeda among the extremist groups that could harm Khan.
The government says the assassination attempt was the work of a lone wolf now in custody, with police leaking a "confession" video by the junk-shop owner saying he acted because Khan was against Islam.
But Khan, a former international cricket star with a playboy reputation before he married, said he has long warned the government would blame a religious fanatic for any attempt to kill him.
Saturday's rally takes place two days after the government named a former spymaster as the next military chief.
General Syed Asim Munir's appointment ended months of speculation over a position long considered the real power in the nuclear-armed Islamic nation of 220 million people.
Munir served as chief of the Inter-Services Intelligence agency under Khan, but his stint ended after just eight months following a reported falling out.
Pakistan's military, the world's sixth-largest, is hugely influential in the country and has staged at least three coups since independence in 1947, ruling for more than three decades.
Since being ousted, Khan has staged a series of mass rallies across the country, drawing huge crowds.
Saturday's gathering is expected to be one of the biggest yet.
Convoys of PTI supporters were streaming in from around Pakistan, with buses, trucks and cars bearing party flags.