Graeme McDowell fell behind for the third day running as he battled with Korean Y E Yang for a place in the quarter-finals of the World Golf Championships-Accenture Match Play Championship in Tucson.
Northern Ireland's US Open Champion came back from losing the opening hole to beat both Heath Slocum and Ross Fisher, but a bogey at the short third saw him go one down to the 2009 US PGA Championship winner.
McDowell could go as high as second in the Official World Ranking by winning the title on Sunday, although that depended on Martin Kaymer losing to Hunter Mahan in his third round clash.
Rickie Fowler, who beat Phil Mickelson 6 and 5 on Thursday, lost two of the first three holes to another Ryder Cup teammate in Matt Kuchar, while twice winner Geoff Ogilvy was three down after three to left-hander Bubba Watson.
McDowell went two down at the fourth, won the next, but then bogeyed the short sixth to lose that.
Fowler birdied the same hole to halve his deficit against Kuchar, while a nine foot birdie putt gave Luke Donald the lead over 17 year old Matteo Manassero on the first.
Because of a bad weather forecast for Sunday - snow even - the schedule for the event has been changed so that both the quarter-finals and semi-finals will now be played on Saturday.
The quarter-finals will start at 7.10am local time (2.10pm GMT) and the semis at 11.45am (6.45pm GMT). The final - 18 holes for the first time this year - will then tee off at 12.15pm Sunday (7.15pm GMT).
The semi-finals could well be affected if the predicted 25-35mph winds arrive, and showers are expected during Saturday night as the temperatures drop.
