JAMIE ROBERTS has warned the British and Irish Lions they will face a daunting atmosphere when they travel to Australia for the "ultimate challenge".
A clash with the Barbarians in Hong Kong opens the tour on June 1 before the 37-man squad heads Down Under for the remaining nine fixtures that will climax in a three-Test series against the Wallabies.
Roberts, one of four centres selected by head coach Warren Gatland, insists the Lions must be prepared for an environment made unsettling by hosts who are desperate to win.
"In a foreign country like Australia it can be quite intimidating. It will be a daunting atmosphere," the 26-year-old said.
"There's 37 players, plus staff, against a nation.
"It's back to the walls stuff from minute one, like it is on every Lions tour.
"It's the ultimate challenge in rugby."
Roberts will be competing with Brian O'Driscoll, Jonathan Davies and Manu Tuilagi for a place in the Lions Test team when the series opens in Brisbane on June 22.
And he is full of admiration for the achievements of O'Driscoll.
"Brian is the epitome of the modern centre," he said.
"His skill set is superb. To go on a fourth Lions tour is special."