SOUTH West toppled defending titleholder Warrnambool (1) yesterday as its undefeated march through the Warrnambool Colts Country Week competition gained momentum.A second-wicket partnership of 96 between Ben Grinter (52) and Daniel Nicholson (42) set the platform for a thrilling two-wicket victory in the second last over at Davidson Oval.The result was a crippling blow for Warrnambool (1), which also lost to Hamilton on Tuesday.Set 153 for victory at Davidson Oval, South West was cruising at 1-98 before spinner Leigh Billington dismissed Nicholson and Grinter in quick succession.From there the encounter developed into what South West manager Tim Fitz-patrick described as a good fighting game of cricket by both teams.Luke Mahoney, batting at number five, combined with number 10 Morris Cole to lift their team across the line in the penultimate over.