Geraint Thomas admits he doesn't know what to expect from this weekend's Milan-San Remo.
The Team Sky rider has never ridden la Primavera, and was only selected on Monday night as a last-minute replacement for Michael Barry, who is suffering from a virus.
And Thomas, who impressed during last week's Paris-Nice, told Cycling Weekly he is expecting a challenging afternoon on Saturday.
"It's going to be difficult, especially as I've never ridden a race this long, and have no experience of the hills and the fast run-in to the finish," said Thomas.
"(The Tour of) Flanders and (Paris-) Roubaix are 260km or so, but an extra 40km - particularly with the climbs that come towards the back end of the race - is what makes it so tough.
"But then again, you ride stages in tours throughout the year with limited knowledge, so I'm approaching it exactly the same as I do for those."
Team Sky are already in Milan preparing for the race, and several of their riders trained on the course earlier this month.
As he was not down to start, Thomas didn't take part in the recce, so the Welshman has indulged in videos as part of a crash-course on the classic.
Despite the challenge, he is excited about competing on Saturday, especially as it's unlikely he'll ride any of the classics in 2012.
"My focus towards the Olympics will begin in November, so I want to ride strongly this year while I can, and especially while my form is a good as it is right now."
Edvald Boasson Hagen looks set to be the Sky leader, despite retiring from the Tirreno-Adriatico with a muscle injury, and the British road race Champion was quick to talk up his team-mate's chances.
"It's definitely one of his goals, and he's more than capable of achieving it, especially if he's on form.
"But you can never rule out Garmin-Cervelo, who have so many cards to play with Thor (Hushovd), Heinrich Haussler and (Tyler) Farrar.
"Thor's lead-outs in the Tirreno for Tyler were phenomenal, and Haussler has looked solid in the sprints and climbs so far this year."
Thomas has also backed Mark Cavendish to come good despite the Manxman's performances in the first three months of 2011.
"You can never rule Cav out. He's always one to watch, and whenever the pressure is on he always seems to deliver.
"He's ridden a lot this year - tours in Australia, Qatar, Oman and Italy - and only won once, so perhaps he's holding something back for Saturday."
While Cavendish has struggled, Thomas rode brilliantly in the Race to the Sun, helping both Greg Henderson take a stage and Bradley Wiggins finish third.
"I came off the track (he took part in February's Track World Cup meeting in Manchester) feeling really good, and I think the lead out for Greg came from that.
"My climbing has improved since last year, and I watched my weight over the winter to make sure I started the season off strongly, which enabled me to help Brad" he adds, while admitting he hopes this will help him reach the finish line in San Remo on Saturday evening.
Thomas will also ride the Tour of Flanders and Paris-Roubaix this spring as Sky look to continue their impressive start to the season.
Having scrapped their "one rider, one race" mantra from 2010, the Olympic Gold medallist believes their hard work from last year is paying off.
"We were a new team built from scratch, yet everyone expected us to win everything immediately.
"It takes time to gel on and off the road and I think we're starting to see that in what we've achieved in the first three months of this season.
"The same expectations seem to be there for Leopard-Trek, and they've only just started winning, despite having some of the best riders in the peloton."
Milan-San Remo 2011: The Big Preview
How Milan-San Remo was won
Sky behind Boasson Hagen for San Remo despite injury
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