Ben Crane faces a long Sunday at the St Jude Classic where he will be attempting to turn an overnight four-shot lead into his first PGA Tour victory since 2011.
Crane completed only six holes of his third round when darkness descended at TPC Southwind on Saturday, a birdie at the first followed by five pars moving him to 13 under overall.
In a tournament disrupted by rain breaks, fellow American Troy Merritt played his second round on Saturday and added a four-under 66 to his opening 67. Merritt then picked up two birdies in the first seven holes of his third round to reach nine under for the week, making him the nearest challenger to Crane.
A third American, Peter Malnati, occupied third place on eight under following a second round of 68 and an early birdie in his third 18 holes, in which he reached the seventh hole by the end of play.
Lurking one shot further back are a trio of players who will like their chances heading into the business end of the tournament, with South African Retief Goosen joined on seven under by American Billy Horschel and Colombian Camilo Villegas.
Play begins at 7am local time on Sunday.
Crane, who has won four times on the PGA Tour most recently at the 2011 McGladrey Classic, is not intimidated by the prospect of a marathon day on the fairways.
He said: "I'm excited. What an opportunity I have. Certainly at the beginning of the week I never thought I would have been here so I'll just try to go home, relax, get some food in me and sleep as fast as I can because we got to come back out at 7am and restart.
"I'll just Skype my wife and kids in Dallas, talk to them and read some scripture, try to stay at peace, get a good night's sleep and come out tomorrow and have fun and enjoy the moment."
Sweden's Carl Pettersson leads the European challenge on six under after a pair of 67s and a level-par run through the first seven holes of his third round.
He features ahead of a five-strong group that includes England's Paul Casey and American Phil Mickelson, who next week will be targeting a first US Open title to complete a career grand slam.
With rain and thunderstorms expected in the area on Sunday, Mickelson would not mind if this week's tournament runs into a fifth day.
"I think the best way to get ready for next week's US Open is to get in contention, have an opportunity and (if) that goes into Monday, so be it," he said.
"Having the tournament go to Monday, even Tuesday is not detrimental in anyway I don't think."