The pre-race favourite from Team Jumbo-Visma was the only rider to break the 13-minute barrier on the tough course which concluded on the steep climb to the Santuario della Madonna di San Luca.
The twelfth rider to roll down the ramp in sunny Bologna, Roglic caught two riders before crossing the line in what proved to be an unbeatable time of 12’54”.
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Riding third from last, Yates, who won three stages and wore the pink jersey for 13 days last year, gave his rival a late scare. But the Mitchelton-Scott rider could only take an otherwise impressive second place, 19 seconds down on the winner Roglic.
Also starting in the first wave of riders, Italy’s Vincenzo Nibali (Bahrain Merida) took third place at 23 seconds, while Colombia’s Miguel Angel Lopez (Astana) and Dutchman Tom Dumoulin (Team Sunweb) were tied a further five seconds adrift to complete a stellar top five.

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“I’m super happy,” Roglic said after his victory was confirmed. “I’ve been waiting now for three hours but it’s a really nice feeling.
I didn’t have much of a tactic except to go through the course as fast as possible.
Asked whether he could emulate Gianni Bugno, who led the 1990 Giro d’Italia from start to finish, 29-year-old Roglic remained coy.
“We’ll see how it goes,” he said. “The most important things is that we’re wearing it in Verona at the end. But it’s a good start and I’m looking forward to the next three weeks.”
Dumoulin, the 2017 champion who finished runner-up last year, was first to start the 8km race against the clock in the absence of defending champion Chris Froome.
The former time trial world champion and current Olympic silver medallist was uncharacteristically slow out of the traps, setting what would be only the 18th fastest time after the flat 5.9km section through the city centre.
If 28-year-old Dumoulin set the target time by virtue of being first on the course, his time at the top didn’t last long: fifth on course, youngster Lopez edged ahead in the same time before Nibali, the double Giro champion, shaved five seconds off both riders after rolling back the years with a commanding ride.
But all eyes were soon on the rampaging Roglic, the rider who entered this year’s race off the back of victories in the UAE Tour, Tirreno-Adriatico and the Tour de Romandie.
The 29-year-old former ski jumper took four seconds off Nibali on the flat to set the fastest time at the intermediate check before dancing up the 2.1km climb of the Colle della Guardia to make light work of the maximum 16 per cent gradient.
It soon became apparent that only Britain’s Yates, the Vuelta champion, could knock Roglic off the top step, the Mitchelton-Scott leader opting to roll down the ramp in the last wave of cyclists almost three hours after the Slovenian pace-setter, despite concerns that the weather may close in.
Yates, who came within two days of winning last year’s Giro, had tasted success in the Paris-Nice time trial earlier in the season, and boasted to the world’s media on the eve of the Giro not only that he was the overall favourite but that his rivals should be “s***ing” themselves.
He was the only of the big GC favourites who decided to go out late – and while the rain held off, Yates was unable to spoil Roglic’s party, the 26-year-old starting the climb 18 seconds down on his rival after apparently checking his effort on the flat.
Out of the saddle and on his favoured terrain, Yates dug deep as he powered past the animated tifosi on the climb, but he was one second slower than Roglic on the climb, dropping to 19 seconds in arrears and second place on the day.
“It felt good and that’s it,” Yates said while warming down. “It was calculated. I can’t go full-gas from start to finish. I feel good and we’ll go from there.”
There were top ten rides from Poland’s Rafal Majka (Bora-Hansgrohe), Britain’s Tao Geoghegan Hart (Team Ineos), Belgium’s Laurens de Plus (Team Jumbo-Visma), Dutchman Bauke Mollema (Trek-Segafredo) and Italy’s Damiano Caruso (Bahrain Merida).
But some big-name riders will be licking their wounds after less than a quarter of an hour of racing: Luxembourg’s Bob Jungels (Deceuninck-QuickStep) conceded 46 seconds to Roglic while both Spain’s Mikel Landa (Movistar) and Russia’s Ilnur Zakarin (Katusha-Alpecin) find themselves more than a minute adrift.
Roglic will wear the race’s first pink jersey as La Corsa Rosa continues on Sunday with the 205km Stage 2 from Bologna to Fucecchio which should see the likes of sprinters Elia Viviani, Fernando Gaviria, Caleb Ewan and Arnaud Demare do battle for the win.

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