Lee Westwood fired a 70 for a three-under total of 210 to lead by two from Tiger Woods, who had a 72, and Hunter Mahan, who had a 68, equalling the best round of the day at the British Open.
The American started the day with a one stroke lead, saw six different players overtake him, and then rebounded at the death to move back ahead by the smallest of margins on one-under 209.
Haas fired a five-under par 67 while Cink, who has not won since defeating Tom Watson in a playoff at the 2009 British Open, shot a 68 to stand atop the leaderboard on 11-under 205, both nine strokes ahead of World No. 2 McIlroy.
Steve Wheatcroft, who booked his place in the field in a Monday qualifier, topped the leaderboard with a second-straight 67 for 10-under par 134.
The 37-year-old Woods posted his 17th career WGC victory, though it was only his first in four years. He has not won a major title in almost five years but hopes to change that with a win in the 77th Masters running April 11-14.
Mahan was the first defending champion to return to the final since 2006 winner Geoff Ogilvy of Australia was runner-up in 2007.
Not to be outdone, Matt Kuchar reached the semifinals for the second time in three years with steady play, rarely taking himself out of position.
Donald was the top seed in his quarter and third seed overall in the 64-man field behind world number one McIlroy and number two Woods, who both fell in the snow-delayed first round on Thursday.
Ireland's Shane Lowry, an old friend of the Northern Irishman from their amateur days, defeated the two-times major winner 1-up with the aid of chip-ins at the 11th and 12th holes at Dove Mountai.
McIlroy pulled one back at 14, but conceded the 15th after finding a series of bunkers. McIlroy then birdied the par-three 16th for a win, but they halved the last two holes with pars, and Lowry emerged victorious.
McIlroy, Woods, England's Luke Donald and American Brandt Snedeker would be top seeds if their ranking position holds.
Indian golfer Arjun Atwal flirted with danger when he stumbled to a bogey on the last hole but still managed to make the weekend cut in the AT&T National here.
Juan Monaco indicated he will be a threat to the big-name players at the upcoming French Open by claiming his second clay court title of the season with victory at the U.S. Men's Clay Court Championships.
US second seed John Isner outlasted Spanish third seed Feliciano Lopez 6-7 (5/7), 7-6 (7/4), 6-3 on Saturday to reach the final of the $442,500 ATP US Men's Clay Court Championship.
Four days after losing the Masters in a playoff, Louis Oosthuizen will try to overcome disappointment and fatigue when he tees up on Thursday in the first round of the Malaysian Open.
Rory McIlroy is counting on some parental guidance to take his revenge on Augusta National at the Masters tournament this week.
South African Louis Oosthuizen posted a second straight 66 on Saturday to take a two-shot lead over Hunter Mahan after three rounds of the US PGA Tour's $6 million Houston Open.
England's Brian Davis and South African Louis Oosthuizen shared the clubhouse lead on Friday as darkness stopped play in the second round of the rain-hit Houston Open.