Steve Stricker's 45th birthday was not going according to plan in Tucson as he quickly found himself two down to South African Louis Oosthuizen at the World Golf Championships-Accenture Match Play Championship.
Stricker beat fellow American Kevin Na in the first round, but 2010 Open Champion Oosthuizen almost drove the green on the 393 yard fourth and after making birdie there needed only a par four at the seventh to double his advantage.
Three successive birdies from Hunter Mahan swept him two up on Korean Y E Yang - Graeme McDowell's conqueror for the second year in a row - after six, while Scots Martin Laird and Paul Lawrie were on level terms after the early stages of their matches.
Laird was playing 18 year old Italian Matteo Manassero and Lawrie, having taken care of England's Justin Rose, faced 20 year old Japanese star Ryo Ishikawa.
England's Robert Rock was off to a sticky start against American Mark Wilson, losing the long second and then conceding the 208 yard third.
Wilson dropped a shot on the fourth, but Rock was three down and in deep trouble after bogeys of his own on the sixth and seventh.
Laird and Lawrie, on the other hand, got their noses in front, Laird turning two ahead and Lawrie taking a one up lead for the third time in the game with a birdie on the seventh.
Third seed Lee Westwood, never behind in beating Nicolas Colsaerts in the opening round, birdied the opening hole to draw first blood against Swede Robert Karlsson.
Westwood has never made the third round in 11 previous attempts, but he was firmly on course to do so after going two up with a birdie on the long second, three up when former Ryder Cup team-mate Karlsson three-putted the fifth and then four clear after Karlsson was plugged in a bunker and did not get out at the first attempt.
Laird was back to one up after bogeying the 219 yard 12th and Lawrie held the same advantage after ten, winning the ninth with a par four, but then dropping a stroke at the start of the inward half.
Rock birdied the long eighth to be only two down, but conceded the next, while Tiger Woods was one up after four on fellow American Nick Watney. Woods lost the first to a birdie, but replied in kind on the next and par was good enough at the fourth.
For the second day running second seed Rory McIlroy was in the penultimate game and he halved the first with Dane Anders Hansen.
