NEW YORK (Reuters) - Jason Bohn celebrated his birthday on Saturday by snatching a handy three shot lead after the third day of the rain-interrupted New Orleans Classic at Avondale, Louisiana.

The American, who turned 37, was cruising along at 12-under-par when bad light stopped play as tournament organizers desperately tried to make up time after two days of torrential rain.

Bohn had only completed six holes of his third round when darkness fell and faces the prospect of playing 30 holes on Sunday.

"Another long day, it's going to be," he told a news conference.

"We've just got to stay patient. That is the thing. You have to wait for your opportunities out here."

Australia's Greg Chalmers and Alex Cejka of Germany were tied for second at nine-under when play was suspended, with a group of five more players one shot behind them.

None of the 75 players who survived the cut were able to finish their third rounds after lightning storms and heavy rain washed out most of Friday's action and parts of Saturday.

As soon as the second round finally ended late in the afternoon, the players were sent back on to the course to get in as many holes as possible before nightfall, playing in groups of three and starting at the first and 10th tees.

Bohn, chasing his second PGA Tour win after winning the BC Open five years ago, led by four shots at the halfway mark after carding a second round five-under-par 67, that featured birdies on each of his last three holes.

He dropped a shot when he bogeyed the opening hole of his third round but got it back with a birdie at the second. He parred the next four and was left with a 17 foot birdie putt on the seventh when play was called off.

"The start of my third round, I kind of hit a couple of loose shots. I think it's a little fatigue," he said.

"I wasn't mentally focused on where I needed to be. So good night's rest, good meal, and I think tomorrow will be a completely different day.

Australia's John Senden and American Jeff Overton were tied for second at eight-under at the end of the second round but failed to improve their scores and were overtaken by Cejka and Chalmers.

The German birdied two of six holes in his third round, and Australian Chalmers bogeyed the first after a long wait in the clubhouse then reeled off four birdies in the next six holes.

"I've had a pretty relaxing day," Chalmers said. "Sitting around watching TV, bored out of my mind for about eight hours. Then came out and played seven holes, six holes really well, and one hole just average."

(Writing by Julian Linden; Editing by Patrick Johnston)