Despite an eagle on the long 18th - his ninth hole of the second round - Woosnam, winner in 1996 and runner-up to Thomas Bjorn last year, slumped to a 78 in the blustery conditions. It dropped the 40-year-old ex-world number one and Masters champion, now 39th in the rankings after 18 barren months, down to the five-over-par mark of 149 and on his long way home.
"That was shocking - I can't hit it out of my shadow," said Woosnam. "It's a little bit more than rustiness, and I'm not really in the mood to talk about it right now."
Also out was his former Ryder Cup team-mate Sam Torrance. Doubtful before the start because of shoulder trouble, the 45-year-old Scot could add only a 79 to his opening 78 for a 36-hole total of 157, 13 over.
Els had injury worries of his own last season, thanks to a troublesome back, but now appears fit.
Two weeks ago he won the South African PGA title in Johannesburg and now another victory is already in his sights after a brilliant 66 - a score matched only by defending champion Thomas Bjorn - lifted him clear of the field.
Els, the world No 5, stands on the 13-under-par total of 131 at halfway, with first day pacesetter Jarmo Sandelin (71) now sharing second place with Australian Peter Lonard (67) on nine under.
Four successive birdies around the turn put Els in command, and after a massive 370-yard drive at the downwind 18th set up another, he is now odds-on to take the pounds 108,000 first prize on Sunday.
Former English amateur champion Roger Winchester, back on the European tour after five years of struggle, had shared second place with Els overnight, but managed only a 74 to drop to joint ninth place on five under.
Local knowledge proved a useful weapon as Britain's Lisa Hackney bounced back to form with a five-under-par 67 in the second round of The Office Depot Tournament at Ibis Golf and Country Club in West Palm Beach, Florida.
Solheim Cup star Hackney missed the cut in the opening two tournaments of the season in Florida, but she succeeded with a round of four birdies and an eagle, giving her a four-under total of 140, four shots behind the joint leaders, Karrie Webb of Australia and the American Betsy King.
In Arizona, Justin Leonard hit a 4-under 67 on Thursday to beat the darkness and give him a one-shot lead over Paul Azinger in the suspended first round of the Phoenix Open.
Beginning his second tournament of 1999, Leonard recorded his fifth straight round below par. He tied for fifth at the season-opening Mercedes Championships, carding no round worse than 72 on the par-73 course.
A one-hour delay due to early frost caused play to be suspended by darkness with 45 golfers still on the course in Scottsdale.
David Duval, who had a final-round 59 in last week's Bob Hope Classic and is already going for his third tournament win of the year, was two over after 16 holes, while Tiger Woods was two-over after 14.