On the eve of his meeting with US President, George Bush, on Wednesday, his own president decided to pull the rug from under his feet. President Chandrika Kumaratunga sacked three key ministers and suspended parliament.
While Wickremesinghe, 54, was preparing for his second meeting with Bush in two years, troubles were mounting at home with Kumaratunga cracking the whip and taking over defence, police and the state-run media.
The prime minister is credited with rendering international the peace process and also receiving unprecedented foreign backing for his efforts to politically end three decades of ethnic bloodshed that has claimed more than 60,000 lives.
He has built a personal rapport with Sri Lanka's immediate neighbour India and returned from a visit to New Delhi last month with agreements on a comprehensive economic partnership and defence.
Wickremesinghe roped in Japan, the country's main financial backer to virtually underwrite the island's Norwegian-led peace process with hard cash and involved the European Union as a key player.
The foreign backing resulted in Wickremesinghe winning $4.5 billion in aid pledges when he addressed a donors' conference in Tokyo in June.
Praise for economy
In the past few months, brokers at the tiny Colombo Stock Exchange (CSE) had been trying to keep track of the tumbling records. The market zoomed by nearly 80% in the past year.
He came to power in December 2001, promising peace and economic prosperity. The economy which recorded an unprecedented 1.5% negative growth in 2001 turned around to register a 4.0% growth last year.
Interest rates and inflation have fallen to a single digit and the country's foreign reserves have gone up, while the local rupee had been appreciating against the dollar for the first time in two decades.
“His economic management may be sound, but he should have been more assertive in dealing with the president from the start"
Broker at the Colombo Stock Exchange
“His economic management may be sound, but he should have been more assertive in dealing with the president from the start," an exasperated broker at the Colombo Stock Exchange said.
His own supporters accuse him of not moving to impeach President Kumaratunga earlier.
Markets began falling onTuesday with news that President Kumaratunga had rejected a Tamil Tiger blueprint for peace in the island.
Even as his problems with Kumaratunga were on the boil, he warned both the president and the Tamil Tigers that the country could go down a slippery slope unless they worked towards peace.
“Unless we succeed this time with all of the international and national goodwill we have received, then we will be consigned to the backwaters of history for a further 30 or 40 years," Wickremesinghe said.
“Our people will become increasingly impoverished, our industries will struggle to compete in the world markets and many more people will die in a conflict without meaning .”
He is expected to return home on Friday to grapple with the toughest challenge to his leadership, even as peace broker Norway tries to arrange a fresh face-to-face meeting between the Tigers and the Colombo government.
The Norwegians will first have to figure out who is running the government.