UPDATE 2-Wal-Mart overseas profit climbs, UK's Asda shines

* Q3 international underlying operating profit up 9 pct

* Q3 international underlying sales up 12 pct

* International growth led by Britain, Mexico, Brazil

* British unit Asda Q3 underlying sales up 5.6 pct

* Asda, Tesco lock horns on pre-Christmas price cuts

(Adds Wal-Mart, Asda, Tesco comment, more detail, background)

By Mark Potter

LONDON, Nov 12 (Reuters) - Wal-Mart Stores Inc (WMT.N), the world's biggest retailer, posted a 9 percent rise in quarterly underlying profit at overseas businesses, outperforming its U.S. operations with strong growth in Britain, Mexico and Brazil.

Asda, the British business, and larger rival Tesco (TSCO.L) also traded blows on price cuts heading into the key Christmas selling season, which Asda finance chief Judith McKenna warned could be the most competitive for a decade. [ID:nLC398949]