Yang sends McDowell tumbling out in Tucson

Yang chipped in at the 16th to complete a 3&2 victory over the US Open champion and will next play American Matt Kuchar. Luke Donald and Miguel Angel Jimenez were on course, however, to take the European flag into the quarter-finals. Donald was five up with six to go on 17-year-old Italian Matteo Manassero and Jimenez seven up after ten on American Ben Crane.

McDowell's fate was sealed when Yang chipped in for another birdie at the short 16th for a 3&2 victory that set up a match against Kuchar.

Martin Kaymer, who needs to reach tomorrow's final to replace Lee Westwood at the top of the rankings, instantly fell two down to American Hunter Mahan but birdied the next, while Jimenez got off to a spectacular start against Mahan's fellow countryman Crane. Kaymer was in more trouble after he blasted two shots out of bounds into the desert at the 11th and fell two down to Mahan,

Donald, never behind as he beat Charley Hoffman and Edoardo Molinari in the opening two rounds, marched into a four-hole lead after only seven holes against 17-year-old Matteo Manassero.

The teenage Italian is the youngest player ever to compete in the event and was on a real high after knocking out Steve Stricker and Charl Schwartzel. But the 2009 British amateur champion, already a European Tour winner in his nine-month-old professional career, could not match Donald's birdies at the first and fourth, bogeyed the next and then saw his opponent fire in another superb approach at the seventh.

Rory McIlroy had been crushed 8&7 by Crane, but the boot was on the other foot as Jimenez took the first four holes, three of them with birdies. Because of a bad weather forecast for tomorrow morning - with a chance of snow even - the schedule for the event has been changed so that both the quarter-finals and semi-finals will now be played today.

The quarter-finals will start at 7.10am local time (1410 GMT) and the semis at 11.45am (1845 GMT).

The final, 18 holes for the first time this year, will then tee off at 12.15pm tomorrow (1915 GMT).

Donald lost the long eighth, but holed from 20 feet at the next and won the 10th as well with a par to move five up.American Bubba Watson and Jimenez both held the same commanding lead after 13 and eight holes - Watson was facing twice winner Geoff Ogilvy and he was the first player into the last eight, thumping Ogilvy 6&4, and he was quickly followed by Ryder Cup team-mate Matt Kuchar, who beat Phil Mickelson's conqueror Rickie Fowler - another of the beaten side at Celtic Manor - 2&1.

L Donald 5 up on M Manassero (through 12)

M Kaymer 2 down to H Mahan (through 11)

N Watney and R Moore, A/S (through 12)

B Crane 7 down to M Jimenez (through 10)

YE Yang bt G McDowell 3 and 2

G Ogilvy bt B Watson 6 and 4

R Fowler bt M Kuchar 2 and 1

J Fay and J Holmes A/S (through 13)