Marc Leishman and Tiger Woods will need to go low on Sunday to have any chance of winning the PGA Tour's Quicken Loans National, after ending the third round six shots behind co-leaders Francesco Molinari and Abraham Ancer.
Italian Molinari and Texas-born Mexican Ancer each handled the scorching heat on the TPC Potomac at Avenel Farm to be 13 under and two shots clear of their closest challengers.
Australian Leishman had three birdies and two bogeys in his one-under-par 69 to end Saturday at seven under.
After starting his round with a bogey, Woods reeled off four successive birdies to get to eight under after seven holes but eventually signed for a 68 to join Leishman and four others in a tie for 10th.
"It was frustrating because I thought 10 under would have been a good score for me to end at for the day and I could easily have got that on the back nine," Woods said, in a video released by the PGA Tour.
Ancer birdied two of his last three holes for the lowest score of his career, to match the course record eight-under 62, giving the 27-year-old his best shot at a maiden PGA Tour victory.
Ancer has never been in the top 10 going into the final round in 22 previous starts.
Molinari, who birdied the final two holes for a five-under-par 65, is also going for his first official PGA Tour victory, though that comes with an asterisk.
He won a World Golf Championship in Shanghai in 2010, though the PGA Tour did not recognise the HSBC Champions as an official win until a year later.
Molinari has five European Tour victories, has played on two Ryder Cup teams and is No.17 in the world rankings.
"It's where I want to be," he said, referring more to his position on the leaderboard.
"I would have been happy with even 11 or 12 under. The main thing today was to stay close to the leader, so I've done a very good job of that."
Conditions have been changing since the opening round with so much sun, no rain and fairways that are getting faster. That was more bothersome to Ancer than the heat.
"I grew up in Mexico, in the north part of Mexico where it's very hot," he said.
"Didn't bother me. I would rather play in this than cold weather."
Zac Blair's round of 66 and Ryan Armour's 68 kept them in the hunt at 11 under, with Ryan Landry one shot further back after a 65, and another American, Kevin Streelman, shooting a 67 to sit nine under.
Rickie Fowler, the only player inside the top 10 at the TPC Potomac, had a 69 and is eight shots off the lead.