GOLF: Maybe it's the timing - two weeks before Christmas - but upgrading the World Cup, which starts in Mexico on Thursday, to a World Golf Championship event has not had the desired impact this time round. Tiger Woods will be missing, as will the defending champions Ernie Els and Retief Goosen.

All of which means that the United States - represented by Phil Mickelson and David Toms - will be hot favourites to extend their country's roll of honour in an event they have won more often than anyone else. Confined to 24 countries - with two-man teams playing two rounds of foursomes and two rounds of fourball - the four-day tournament will be played at the Jack Nicklaus-designed Vista Vallarata course at Puerto Vallarta.

This will be the sixth successive year that Padraig Harrington and Paul McGinley have represented Ireland. Under the qualifying criteria - the top two players off the official world rankings - Darren Clarke could have teamed-up with Harrington, but he opted not to play so that the combination could be kept intact.

In their five previous appearances, Harrington and McGinley have recorded four top-10 finishes, and Harrington knows how important the right team chemistry is in this format.

"The biggest difficulty is that you've got a two-man team and it doesn't matter how good one guy's form is . . . the pressure is on the other player to keep up to those standards. If he misses a few putts, it can really drag the team down. It is a tough, tough format."

Ireland are the third seeds in the event, behind the United States and, surprisingly, Fiji.

Defending champions South Africa are represented by Tim Clark and Rory Sabbatini.

After Ireland, the next highest ranked European team is Sweden - represented by Carl Petterson and Niclas Fasth - who are eighth.

Wales will be represented by Ian Woosnam and Bradley Dredge, but there have been late changes to the Scottish and English teams. Andrew Oldcorn was forced to withdraw last week because of a damaged disc in his back and his place on the Scotland team has been taken by Alisdair Forsyth, who teams up with Paul Lawrie.

England's Nick Faldo has also pulled out due to injury, and his place has been taken by Paul Casey, who pairs up with Justin Rose.