Dunedin - Fullback Paul Williams scored two tries to help the visiting Blues to a 19-15 victory over the Highlanders in an error-ridden Super 14 clash at Carisbrook in Dunedin on Friday.Rene Ranger added the Blues' third try, less than five minutes after Williams scored his second, and Stephen Brett converted two of the tries."I think it gave us a bit of self belief and the confidence went a long way in that second half," Blues captain Keven Mealamu said of their two quick second-half tries."It's one of the toughest matches in Super 14, so we're delighted with the result."Fullback Israel Dagg and flyhalf Michael Hobbs scored tries for the Highlanders, with Hobbs converting one try, while Dagg also added a penalty.The visitors opened the scoring when Williams barged through Otago winger James Paterson to score in the corner after eight minutes and Brett converted to give Auckland a 7-0 lead.Paterson made immediate amends when he created the extra man in a simple attacking move from a lineout and fed Dagg to score in the corner.Highlanders flyhalf Hobbs scored his third try in two weeks when he barged over from in close after Blues prop Tony Woodcock committed a handling error on his line.Hobbs converted to give the Highlanders a 12-7 lead at the break, though both he and Brett missed several attempts at goal as they struggled with the swirling wind.The former Blues player then missed a penalty early in the second half and from the ensuing restart, Williams' clearance kick was partially charged down, putting all of the Auckland players in front of Williams onside.All Blacks prop John Afoa gathered the ball and fed Williams, who cantered over for his second try. Brett added his second conversion to give the Blues a 14-12 lead.Ranger then scored the Blues' third try but Brett missed the conversion from close to the posts.Dagg brought the score to 19-15 when he slotted over a penalty from in front with just over 20 minutes to go.