CARLTON'S apparent march to a first-ever top-flight title hit the buffers when the Edinburgh side slumped to defeat at the hands of West.
The previously unbeaten leaders went into this Grange Loan clash as red-hot favourites against a West side battling to avoid the relegation play-offs.
However, former Scotland batsman Dougie Lockhart turned back the clock with a superb century to the Hamilton Crescent outfit to their best win of the season.
Having been put into bat, West progressed cautiously at first but Lockhart, with excellent support from Ian Young and Colin de Grandhomme, propelled his team to a challenging 275-3.
Skipper Young contributed 58 while de Grandhomme, the New Zealand professional, gave his most impressive batting display to date.
With the platform having been laid by Lockhart and Young, de Grandhomme opened out to hit a 62-ball 89 which included six fours and four maximums. Lynchpin Lockhart went on to carry his bat for an unbeaten 107, his 140-ball knock including 14 boundaries and one six.
Another former Scotland batsman, Cedric English, matched Lockhart with 109 for the hosts. However, English had no meaningful support from his star-studded team-mates and Carlton were eventually bowled out 26 runs short of their target.
Fourth-placed Heriot's suffered a derby defeat to Grange, who kept their own top-four hopes alive in the process. Batting first, Heriot's made 198, with skipper Steve Knox top-scoring with 81.
In reply, Grange lost Legga Siaka to the first ball of the innings but recovered through Saltires Neil McCallum (67) and Gregor Maiden, who made 41. New Zealand pro Warren McSkimming saw them home to a six-wicket win with 31 not out.
Arbroath stepped-up their challenge with a thoroughly impressive win over Watsonians at Myreside.
In another high-scoring encounter, the visitors had two centurions as they rattled-up 296-5.
Sri Lankan Harsha Vithana and Aussie Harry Byrnes Howe both hit the three-figure landmark as the home bowlers toiled.
Scotland youngster Ewan Chalmers responded with 101 for the hosts but Craig Ramsay's five wickets sealed a famous 74-run win for Arbroath who have emerged as genuine title challengers.
Forfarshire also remain firmly in contention after they got the better of the north-east derby against Aberdeenshire at Forthill.
Chasing 209 for victory, the Broughty Ferry side got there with four wickets and two overs to spare.
Graeme Garden put the hosts on course with 36 before Umair Mohammed's 44 steered them over the line.
Earlier, Rohan Damle top-scored - also with 44no - for Aberdeenshire.
Elsewhere, Uddingston completed a league and cup double over Clydesdale at Bothwell Castle.
Ricky Bawa, the home captain, had this week bemoaned the apparent lack of strength of clubs in the west of the country - citing Dale as the only team likely to challenge those in the east and north.
However, having knocked the Titwood club out of the Scottish Cup earlier in the month, Uddingston again proved too good for their Glasgow visitors.
Wickets were shared about as Dale were dismissed for a lowly 148 in less than 43 overs, skipper Kasim Farid top-scoring with 30.
Uddingtson did not have things all their own way as Pakistani professional Nazar Hussain inspired a Clydesdale fightback with three wickets.
However, Saltires and former Warwickshire all-rounder Calum MacLeod displayed his growing prowess with the bat in stroking a match-winning unbeaten 57 while Alecz Day contributed 30.
Drumpellier went into their clash with Stirling at New Williamfield having failed to win since the opening day of the season.
However, they overcame the handicap of being without professional Jeevantha Kulatunga and skipper Graeme McLaren to defeat their hosts by 52 runs.
Andi McElnea emerged as the unlikely bowling hero in Ayr's much-needed win over Stoneywood-Dyce at Cambusdoon. Like Drumpellier, the Ayrshiremen had won just once going into yesterday's action. A second success was by no means certain when they made just 182-5, New Zealander Michael Papps top-scoring with 35. However, opening batsman McElnea showed his skills with the ball to claim 4-29 as the Aberdonians were dismissed for just 117.
Freuchie had hoped to give themselves a morale-boosting win ahead of today's Village Cup quarter-final against holders Sessay.
Instead the Fifers slumped to a 77-run Championship defeat against Edinburgh Accies at Pleasure Park.
Visiting skipper Kean Woodmansey did the damage with five wickets as Freuchie were bundled out for just 115 in response to Accies' 192-8.
Leaders West Lothian went down by eight wickets to East Kilbride at Torrance House.