They start the Giro d'Italia on Saturday having moved into a new dimension over the past 12 months, with a major Tour leader who went from near-miss to confirmed winner in 2012. Not Team Sky and Bradley Wiggins, but their rivals at the American squad Garmin, who travelled to Naples in confident mood and with the defending champion Ryder Hesjedal, a former mountain bike racer from British Columbia.

The Canadian's win at the Giro last year came from left field, but it was a breakthrough moment for Garmin, founded in 2008 by Lance Armstrong's former team-mate Jonathan Vaughters and the Scot David Millar. The team had regularly posted riders in the top 10 of major Tours – Hesjedal among them, with his sixth in the 2010 Tour de France – but needed to get to the top of the podium. Given their philosophy from the start has been founded on anti-doping, it was also a breakthrough for the entire sport.

Millar, for one, is in bullish mood, although he will arrive at the Giro only on Friday after leaving his departure until the last minute as his wife, Nicole, is expecting their second child. Pointing to Hesjedal's dominant form in the Liège-Bastogne-Liège Classic a couple of weeks ago, where the Canadian set up his team-mate, Daniel Martin, for the win, Millar says it is "realistic" that Hesjedal could defend his title.

As for last year's win: "That should earn us a bit of respect, but there is responsibility that comes with it. Usually we just go in and see how it unfolds, but here we need to be more switched on, Tour de France style."

The team's other Briton, the directeur sportif Charly Wegelius, has extensive experience of the Giro from his racing days in Italy and says Garmin cannot repeat the feat of last year, when Hesjedal was unfancied – known as a consistently strong racer, but not a big winner – until he emerged in the final week. Tactically, it was, Wegelius says: "A one-trick wonder."

This year Hesjedal will be a marked man, and although he says he knows how to repeat his win of last year, he concedes the enhanced quality of the 2013 field, including both Wiggins and Italy's best stage racer Vincenzo Nibali, means: "I could conceivably ride better than I did last year and still not win the race."

Ironically, Garmin will start the Giro without their biggest star of the spring, the young Irishman Daniel Martin, who won the Tour of Catalonia and the Liège-Bastogne-Liège. Wegelius would have liked to see him in the race – particularly in view of the fact that it will start in Ireland next year – but Martin's spring was planned without the Giro so his schedule was heavy even without the Italian race, while he suffers from allergies that might have affected his performance in Italy.

The conventional view is that Garmin are the polar opposite of Sky – chilled out and fun, while Sky stress about marginal gains. The reality is not that simplistic, but the history between the two teams cannot be denied – it was at Garmin that Wiggins made the breakthrough as a Tour de France contender in 2009, and that was followed by an epic struggle between the two teams to secure his signature for 2010.

Wegelius makes the point that Garmin's laid-back reputation does not stop them "racing at 100%".

He adds: "We race seriously but don't take ourselves too seriously. Our skinsuits are as tight as the next guy's but there is a relaxed atmosphere and that's our strength. There is no reason to become investment bankers just because we won the Giro."

Garmin's directeur sportif has no doubts about the capacity of Wiggins, with whom he raced regularly until his retirement in 2011. "He has enough experience from his early years, when he rode the Giro many times … he knows the race and the ins and outs of it," says Wegelius.

"It's a classic Giro route, all weighted to the last week, but compared to the Tour there are lots more 'ambush stages' – they don't look much on paper but you can suddenly hit a decent climb or small roads."

The inclusion of a 56km time trial in the opening half is, he says, "a massive 'please-visit-us sign' from the organisers to Brad."

He adds: "The biggest threat to Brad is how steep the climbs are – they are always going to be a problem for him. Then there is the issue of time bonuses, which is a new element." The fact that each stage win is worth 20sec off a rider's overall time will give Nibali in particular a chance to gain time on Wiggins.

Wegelius feels that most teams will look to Sky to keep control of events, given the way they have raced this season and last. "Clearly there's going to be poker played – every team wants to conserve its reserves. Sky can try to be inventive about controlling the race but if you have the top favourite you need to step up to the plate. They showed at the Tour they have the power to do it. It's their race to lose."