Peter Sagan kept his hands on the rainbow jersey after overcoming the field and the stifling conditions on a flat 257.5-kilometre course in Doha on Sunday.
The Slovakian roared through the pack in a bunch sprint to leave Briton Cavendish banging on his handlebars, while Belgium’s Tom Boonen took third.
On a circuit that was for the most part featureless and almost entirely without spectators, the first 100 kilometres of the race offered little of note, beyond the usual jostling.
When things did start to take shape, it was Belgium and Britain who took command, Tom Boonen and Mark Cavendish leading the way.
The early breakaway group was soon reeled in, but it was not long before the heat, combined with an energy-sapping crosswind, began to claim its first victims.
An experienced Germany team was having a bad day at the office, with Marcel Kittel and John Degenkolb calling it quits late on, while Andre Greipel finished down in 42nd.
Britain’s early cohesion had all but deserted them during the middle section, but Adam Blythe rode bravely to boost his team-mate’s hopes of a first title since 2011.
Dutchman Tom Leezer was the first to go off the front of the leading pack with two kilometres left and that sparked a frantic finish.
In the late bid for the line, Cavendish lost road position and got caught behind Michael Matthews, but Sagan had no such issues.
With a gap ahead of him, Sagan showed his raw power to take the glory in front of a delighted contingent of Slovakian fans.