"Ah here, the only 'permutation' I want is one in my hair," said Irish assistant manager John McDonnell, patting his head, a curl-free zone, after being presented with the seemingly limitless number of ways Ireland can finish first, second, third or fourth in their World Youth Cup pool.

"It'd wreck your head - we've just got to go and play the game, you can't play for a draw or anything like that, just try to win it. You'd be distracted otherwise."

McDonnell, then, is reluctant to consider anything but a victory against Mexico tomorrow (4.30 Irish time), despite a draw (which would guarantee a top-two finish in the group) being enough to put the team through to the second round.

Even a defeat, by a single goal, would suffice and with the four best third-placed teams in the six groups also going through to the second stage there could be an added safety net for the team - if Ireland finished in third place, on four points, and two of the third-placed teams from the other five groups failed to reach that total Ireland would go through.

A win or a draw, then, against Mexico would ensure a top-two finish in the group - the result and scoreline between Saudi Arabia and Ivory Coast determining whether Ireland would finish first or second.

What if Ireland and Ivory Coast both lose, by more than one goal and by the same scoreline? Lots would then be drawn to determine who would finish third. Ireland, though, have the advantage of playing after Saudi Arabia and the Ivory Coast tomorrow, so will know exactly what they need from the game against Mexico to guarantee their place in the last 16.

But, as McDonnell put it, the permutations would "wreck your head". A win or a draw would simplify the issue, and put Ireland - no calculators needed - into the second round.

The winners of Ireland's group play second in Group D (Colombia, Egypt or Japan) in Al Ain on Tuesday. The second-placed team in Ireland's group play the winners of Group F (Paraguay, Germany, USA or Korea) in Dubai on Monday.