American Chad Campbell faces a gruelling 32-hole US Masters marathon today after his overnight lead was cut to one shot in Saturday's weather-interrupted third round.

Three clear at the start of a truncated day, the 31-year-old Texan moved to eight under with birdies on the first two holes.

However, he then bogeyed the par-four third, after failing to reach the green in two, and dropped another stroke at the fourth before play was halted in fading light at Augusta National.

Hot on Campbell's heels at five under were South African Tim Clark, who reeled off three birdies in the first five holes, and American Rocco Mediate, two under for the round after four holes.

Defending champion Tiger Woods, chasing his fifth green jacket, was at three under after nine holes, level with Ireland's Padraig Harrington, after six, and 2004 champion Phil Mickelson after five holes.

"It's going to be tough but I don't think winning any major is easy," Campbell said of the task facing him.

"It's going to be a little tougher walking this course. Eighteen holes is quite a chore so, with 32, we've got our work cut out for us.

"I'll get a good night's rest and be ready for tomorrow."

World number one Woods, bidding for a fourth Masters title in six years, was happy with his position after making two birdies in the first nine holes.

"I know I'm in condition, it's just a matter of execution," the 10-times major winner said. "I feel very good. In soft conditions like this you can make some birdies.

"I need to make a move on the back side tomorrow."

Earlier, play was suspended for four-and-a-quarter hours due to the threat of lightning and approaching thunderstorms.

Only two more hours of play were possible after the competitors returned to the course late in the afternoon.

The third round will resume at 7.45 am local time (11.45 GMT) today.

With the greens softened by steady morning rain, the players were able to attack the pins late in the day.

Woods almost holed his wedge approach at the par-four third, tapping in for birdie to close within four of the lead.

He then parred the next four holes before picking up another shot at the par-five eighth to go to three under.

Clark birdied the first, hitting driver off the tee and a four-iron for his second to 10 feet, to get to three under.

Mickelson, four off the pace at the start, also birdied the par-four first after hitting a superb shot from the right fairway bunker to within six feet of the flag.

That put him level with Clark in a tie for second place, where they were joined moments later by Harrington, who birdied the second and third.

Clark picked up another shot at the par-five second before horseshoeing out with a birdie attempt from only three feet at the third. However, he drew level with Mediate with a birdie-three at the fifth.

"I couldn't be more pleased with my start," said Clark. "It's going to be a tough, long day tomorrow but it'll be a fun day too."

Mickelson also birdied the second and then rolled in a 10-footer at the par-four third to climb into second place at five under.

The left-hander then bogeyed four and five to drop back.

American Jim Furyk, the 2003 US Open champion, birdied two of the last three holes for a four-under-par 68 to take the clubhouse lead at level-par 216.

Playing at the back of the field with a non-competing marker, Furyk struck his approach to within two feet of the flag at the par-three 16th and then holed a 40-footer on 17 for his fifth birdie of the day.

Sunday's weather forecast is optimistic, with dry and partly sunny conditions expected.