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* Cruden kicks 18 points for world champions
* All Blacks stretch unbeaten run to 20 matches
* Struggling Wales suffer sixth straight defeat
CARDIFF, Nov 24 (Reuters) - World champions New Zealand ruthlessly exposed Wales's frailties with a 33-10 victory at the Millennium stadium on Saturday underpinned by an immaculate display of place kicking from replacement flyhalf Aaron Cruden.
Cruden, a late substitute for Dan Carter, the world's best standoff who withdrew on Friday evening with an injury to his right leg, converted each of his kicks for a total of 18 points.
The win extended the All Blacks' unbeaten sequence to 20 while European champions Wales, who completed a third Six Nations grand slam in seven years last March, have now lost six matches in a row.
Cruden's composed performance and flawless kicking was in sharp contrast to the display of his opposite number Rhys Priestland, who now seems bereft of the confidence and form he showed at last year's World Cup.
Priestland twice kicked penalties dead over the All Blacks line, gifting the ball straight back to them, while Wales also mystifyingly spurned two kicks at goal early in the first half which Leigh Halfpenny could have converted into six points.
They did outscore the All Blacks by two tries to one after the break, but New Zealand already had the game won with 23 unanswered points at the interval and were soon giving their replacements a run before next Saturday's final match of their November tour against England.
Left wing Julian Savea, the world's leading try-scorer this year, atoned for an early knock-on with two flashes of brilliance in New Zealand's first try scored by blindside flanker Liam Messam.
Savea leaped high to tip a Priestland up-and-under back to Israel Dagg then held on brilliantly to a low, fast return pass after the fullback had broken the Welsh line.
When the move broke down near the Welsh line the ball was quickly recycled right to Messam to stroll over for the try.
All three tries went to the forwards with prop Tony Woodcock scoring his eighth international try and lock Luke Romano his first. Woodcock's was a replica of his try in the 8-7 win in the World Cup final against France last year when he thundered through a gap in the middle of the lineout.
Replacement centre Scott Williams and right wing Alex Cuthbert scored the Welsh tries, with the entire XV joining the shove from the lineout which sent the former over the line.
Williams had taken over from the injured Jamie Roberts in a bleak period for the Welsh in the first half during which they also lost lock Bradley Davies and prop Aaron Jarvis, who was taken off on a stretcher, to injuries.
Davies had collapsed on the ground after a stiff arm blow to the neck from All Blacks' hooker Andrew Hore in the opening exchanges which incensed the crowd but appeared to go unnoticed by South African referee Craig Joubert or his assistants.
Joubert did, though, send Cory Jane to the sin-bin for a deliberate knock-on by the New Zealand right wing midway through the second half.
Wales' New Zealand coach Warren Gatland said Davies would have to go to hospital.
"I haven't had a good look at it, I'll leave that to the citing commissioner," Gatland told a news conference. "It doesn't look the best, it looks like he's been caught from behind, whether to a swinging arm or not.
"You don't usually associate the All Blacks as a side that resorts to cheap shots, I hope it's not the case, I hope it's an accident."
Gatland said his side had grown into the game and added he was proud of their second half performance.
"That was how we planned to play in the first half. You have to take some risks against the All Blacks, but it doesn't help when you kick two of those penalties dead," he said.
New Zealand coach Steve Hansen said he was not sure why Wales had decided not to try to kick early points.
"I am sure that is something that they will talk about after," he said. "Our first 50 minutes was very pleasing.
"We had Cory Jane put in the bin in the second half and maybe we kicked the ball a little too much and allowed them to come back at us."
All Blacks' captain Richie McCaw, named man-of-the-match for another totally committed display at the breakdown, said his team planned another big performance against England at Twickenham next Saturday.
"To win by 23 points in a place like this is a great result. It was a reasonable performance but perhaps we did not treasure the ball as much as we could have," he said. (Editing by Ken Ferris)