JOHN O'BRIEN is well acquainted with uphill tasks. As a businessman, he dispatches tourists on biking treks around Glendalough in the Wicklow mountains.

As a sportsman, the Westmeath full back is acutely aware his side face a climb of similar proportions when they play All-Ireland champions Dublin in the Leinster senior football championship at Pairc Tailteann on Sunday.

He is also the man expected to curb Dublin's prodigal son, Joe McNally, recalled to the Leinster champions' fold after a four-year period in the wilderness.

But the underdogs tag is one which fits comfortably with O'Brien, a product of the Westmeath under-age nursery which has reaped enormous benefits in recent years. "We have nothing to lose in this match, we are playing for our pride," he said.

"Of course, you'd probably prefer an easier game to start the championship - but the way I see it is that you are going to have to face Dublin somewhere along the line, whether it be the first or second round, so why not now?

"Being realistic, we will need to play out of our skins to beat Dublin. Every player will have to play to his full potential, but we are looking forward to taking them on," said O'Brien.

Westmeath's victory in the All Ireland minor championship last year gave football in the county an enormous boost, although the truth is that the afterglow doesn't really extend as far as the senior side. None of last year's minors are yet involved at senior level.

However, an indication of the young blood in Sunday's line-up is that eight of the Westmeath players are under 22 and, ironically, the most experienced campaigner, Michael `Spike' Fagan, was a colleague of Joe McNally on Ireland's last Compromise Rules tour to Australia. "Spike adds about 10 years to the average age of the team," said O'Brien.

When Westmeath were managed by Meathman Mattie Kerrigan two years ago they gave the Royal County a rare run for their money in a National League semi-final. This time round there is added spice because Barney Rock is in charge of them against his native county.

"I don't think we really made the progress people expected of us after that Meath match, but Barney's involvement has certainly created plenty of interest in this game and, in a way, deflected pressure away from the players, which is a good thing," said O'Brien.

As for facing Big Joe? When McNally last played in Dublin's colours in a championship game, O'Brien - whose previous face-to-face opponents in the past including Louth's Colin Kelly, Wicklow's Raymond Danne and Meath's Tommy Dowd - had yet to make his debut.

"I don't think you can compare Joe McNally with any of them," he said. "I think he will be my biggest challenge yet. I expect he will be quite a handful."