Not for the first time in Pakistan's history had a favoured general turned against his civilian patron. Things came to a head in 1999 when, under US pressure, Sharif forced General Musharraf to pull back his troops and surrender territory seized from India during the Kargil war in Kashmir.

General Musharraf was livid. But instead of mending fences, Sharif, naive and impulsive, decided to teach the recalcitrant general a lesson.

Pakistan's democratically elected leader was already running out of control - he had turned megalomaniacal after becoming prime minister for a second time in 1997 with an absolute majority in parliament, and was busy cutting down opponents, appropriating power and ruling like an autocrat. He had the constitution amended to deny the nation's president the authority to dismiss the prime minister. He got a law passed that made it impossible for his party legislators to defy his edicts.

When the country's top judge refused to be cowed, Sharif's party thugs, led by his political secretary, stormed the Supreme Court. The chief justice was forced to quit. When a prominent newspaper editor in Lahore criticised him, he had him abducted and charged with treason.

At the time of his ousting, Sharif was trying to push through another constitutional amendment that would have made Islamic law supreme and transformed him into a medieval despot, with the power 'to prescribe what is right and to prohibit what is wrong' on the basis of the Koran.

As human rights activist Asma Jehangir said, Sharif was trying to 'Talebanise' Pakistan.

Finally, hubris made him try to seize control of the army, Pakistan's most powerful and resilient institution, while General Musharraf was out of the country. But the other generals stayed loyal to their chief, and Sharif was suddenly out of power. Barely two years in office, Sharif's popular base had eroded so completely there was hardly any protest. In fact, General Musharraf was soon being hailed as a saviour of the nation.

In an earlier coup in the 1970s, Prime Minister Zulfiqar Ali Bhutto was hanged by his specially chosen army chief, General Zia-ul-Haq. But General Musharraf, after keeping Sharif imprisoned for more than a year, sent him into exile in December 2000 in a secret deal brokered by Saudi Arabia and blessed, it is rumoured, by the United States.

Sharif was to remain in exile for 10 years, and stay out of politics. But after pro-democracy lawyers began agitating this March, undercutting General Musharraf's authority as president, Sharif is tempted to break the agreement and rush home.

He is hoping to seize a historic moment, and emerge triumphant. General Musharraf is now a spurned ruler, while Benazir Bhutto, daughter of the deposed prime minister and Sharif's main political rival, is increasingly being seen as trying to cosy up to the general.

Bhutto has delayed her return as she tries to finalise a deal with General Musharraf. But the drawn out negotiations with the reviled general have rebounded badly on her.

During the last few weeks, Bhutto's popularity has plummeted while Sharif's has soared.

'Anyone challenging Musharraf will be seen as a champion of democracy in Pakistan today,' said Pervez Hoodbhoy, professor of nuclear physics at Islamabad's Quaid-e-Azam University. 'Sharif may not be very bright, but he is benefiting from Bhutto's mistakes.'

Thanks to US President George W. Bush's unpopular 'war on terror', Pakistanis have also vehemently turned anti-American. In her anxiety to clinch an advantageous deal with General Musharraf, Bhutto has begun to openly lobby Washington, even hiring an expensive American public-relations firm for the purpose.

This is again benefiting Sharif, who has now been recast - ironically, considering his record - as a leader with 'self-respect' who will not kowtow to the US. So in an extraordinary twist of history, the man who appeared to be destroying Pakistan's fragile democracy barely eight years ago will now be welcomed back as its saviour.

If all goes according to plan, Sharif will fly back to Pakistan with the hope of eventually reclaiming his old job, while General Musharraf desperately tries to stop him. The tables have truly turned.

'Sher aya!' (The lion has come!) is the chant that will greet Sharif when he lands in Islamabad. But he will not linger in Pakistan's capital. He plans to set off immediately in a rousing motorcade to his country's political heartland and his own personal fiefdom, the elegant city of Lahore in Punjab province.

Punjab not only has more than half Pakistan's population, it is also the province that produces most of the country's military and bureaucratic elite. The 57-year-old Sharif was born into a Punjabi businessman's family who saw their fortunes skyrocket after he entered politics.

Sharif's rise was meteoric largely because of patronage from the military dictator Zia, who was killed in a mysterious plane crash in 1988, when Sharif was already chief minister of Punjab. In the national elections that followed Zia's death, Sharif was defeated by Bhutto, then a rising politician from neighbouring Sindh province.

This was the start of a decade-long game of high-stakes musical chairs between Sharif and Bhutto, resulting in extreme political instability, street violence and frequent elections. Sharif replaced Bhutto as prime minister in 1990; he was replaced by her in 1993; and then he ousted her a second time in 1996.

Now the two leaders are reviving their old rivalry, and anything can happen. Karachi's bookies clearly do not believe that Sharif can have a happy homecoming. They have fixed the odds for his return at a steep 10/1 against. But Sharif knows that now is the best opportunity for him to come in from the cold.

If Sharif gets onto a London-Islamabad flight on Monday accompanied by his younger brother and chief political adviser Shehbaz Sharif, and a horde of journalists, then the president has three choices: send him back to Saudi Arabia, where he began his exile; lock him up in a Pakistani prison; or let him proceed on what will turn out to be an extraordinary victory motorcade to Lahore.

In Islamabad, officials have begun to talk of the 'Bangladesh Minus Two' solution, where the army has tried to sideline the nation's two main political leaders by first sending them into exile, and when that failed, sending them to jail.

With national elections due early next year, can General Musharraf likewise keep out Pakistan's two main democratic leaders?

Whatever view the bookies might take, the nation's political analysts believe that General Musharraf has few options left. 'The middle class is now firmly committed to democracy - look at the sophistication of the lawyers' movement,' said Rasul Bakhsh Rais, political science professor at the Lahore University of Management. 'I'm optimistic about the future of democracy in Pakistan.'