In glorious sunshine at Augusta National, overnight pacesetter Weir carded a four-under-par 68, stretching his lead to four shots at six-under 138.

Northern Ireland's Darren Clarke, two behind Weir at the start of the day, completed a roller-coaster round of four-over-par 76 to finish in second place at two under overall.

Phil Mickelson, chasing his first major title on his 43rd start, carded a 70 to share third at one under with U.S. amateur champion Ricky Barnes, who returned a 74.

Woods, bidding for an unprecedented third consecutive green jacket at Augusta National, had been eight shots off the pace at the start of the day but, in his own words, was right where he needed to be with "a chance in the tournament."

The world number one parred his first two holes of the day, the second and third, but then stumbled at the par-three fourth, where he twice found bunkers before two-putting from 20 feet for a double-bogey five.

He then dropped another shot at the par-three sixth to fall back to five over, and 11 behind leader Weir, before a welcome birdie at the par-four seventh.

But Woods missed a three-foot putt to save par on the par-five eighth and needed to hole out at his last from a similar distance to card a one-over 73 which just kept him in the tournament at five over.

His only professional missed cut was the 1997 Canadian Open and the last time he failed to play the final two rounds of a major was the 1996 Masters as an amateur.

The 27-year-old Woods has now gone 102 tournaments without missing the cut, the third best record on the PGA Tour after Byron Nelson, on 113, and Nicklaus, on 105.

Weir, who reeled off successive birdies before play was finally halted in gathering gloom on Friday, bogeyed his second hole of the morning to slide back to five under -- and three ahead of the chasing pack.

But the consistent Canadian, twice a winner on the PGA Tour this season, birdied the par-five 15th to forge further ahead of his challengers as the fluctuating leader board below him reflected the up-and-down nature of play.

Northern Irishman Clarke, who began the day two behind Weir with eight holes to play, fell back immediately, finding water on the 490-yard 11th to run up a double-bogey six.

He dropped another shot at the par-five 15th but a birdie three on 17 lifted him into second place on his own.

Mickelson, four shots off the lead overnight, was typical of the erratic scoring on quickening greens in the spring sunshine and bogeyed the par-three 12th, his first hole of the day.

The left-hander hit back immediately with birdies on the two par fives -- 13 and 15 -- to move ahead of Clarke into second place.

But the 32-year-old Californian then double-bogeyed the 170-yard 16th after pushing his tee shot into a bunker to slip behind Clarke into third at one under.

Twice champion and Augusta specialist Jose Maria Olazabal carded a 71 to finish at even-par 144, level with four others.