Barrett blunder sees Chiefs overcome Blues to stay unbeaten in Super Rugby

The Waikato Chiefs extended their unbeaten start to Super Rugby Pacific with a 20-13 defeat of the Auckland Blues on Saturday, their victory boosted by an inexplicable blunder from All Blacks star Beauden Barrett.

The competition-leading Chiefs made it six wins from six -- their best start to any season -- built around a brilliant performance from fly-half Damian McKenzie, who appears poised to be a key utility player for the All Blacks at the Rugby World Cup.

McKenzie outplayed opposite number Barrett in a tense derby between two New Zealand powerhouse teams at Hamilton's Waikato Stadium.

Test centurion Barrett struggled with his handling in slippery conditions and landed one shot at goal from three attempts, compared to McKenzie's perfect return from four shots.

However, Barrett's biggest mistake came in the first half when he was put over the tryline but stood on the dead ball line when trying to improve his position.

The rarely-seen gaffe helped the home side build a 17-10 lead at the interval and the Blues couldn't close the gap, foiled by staunch Chiefs defence through much of the second half.

McKenzie was influential from the outset, his grubber kick setting up a try to winger Emoni Narawa with just 22 seconds on the clock.

The 27-year-old's variety of kicks kept the Blues defence guessing while sideline conversions of both of Narawa's tries and a penalty kick from inside his own half were critical in a tight contest.

The Blues tries were scored by hooker Ricky Riccitelli and winger Caleb Clarke in a result that leaves last year's beaten finalists with three losses from six games.

Chiefs co-captain Brad Weber revealed his team had been motivated by the corresponding fixture in Hamilton last year, when the Blues became the