Australian Jason Day, a Masters Tournament runner-up two years ago on debut, holds a one shot lead going into the weekend at Augusta National.
In the last group out, Day carded a 68 to finish six under par, one shot clear of compatriot Marc Leishman and 53 year old former champion Fred Couples.
“Being top of the leaderboard right now is a great honour to have,” said 25 year old Day.
“I’m really looking forward to getting out there the next two days and playing well; I’m just very, very tired.
“When it comes to the weekend I know there are a lot of very good players behind me who are going to play well. I just have to stay patient and focus on what I’m doing and really not worry about anyone else.
“Hopefully I can be there come Sunday. Obviously there’s a lot of pressure on my shoulders being Australian as no Australian has ever won the event even though a few have been very close. So I’ll just try to keep that out of my mind and plug away.”
By failing to birdie the 18th, Day ensured Chinese teenager Guan Tian-lang made the cut on four over under the ten-shot rule, despite the 14 year old earlier being penalised a shot for slow play.
Argentina's Angel Cabrera, the 2009 champion, was two off the lead alongside American duo Jim Furyk and Brandt Snedeker after storming home in 31 with five birdies in his last six holes, while English trio David Lynn, Lee Westwood and Justin Rose were another stroke back on three under.
Jason Dufner, KJ Choi, Adam Scott and Tiger Woods were also three under, 14-time Major winner Woods dropping two shots in the last four holes by three-putting the 18th after seeing his pitch to the 15th hit the pin and bounce back into the water.
Couples, who claimed his Green Jacket in 1992, also shared the lead with Dufner at the same stage last year but shot 75 on Saturday and eventually finished 12th.
Guan, the youngest player in Masters Tournament history, added a 75 to his opening 73 to finish four over par and break Matteo Manassero’s record as the youngest player to make the cut.
World Number One Woods, who shared the lead before a back nine of 38, was left to rue his bad luck on the 15th – his third shot would almost have finished within ten feet had it not clattered the flagstick.
“It looked like I was making birdie and now I have to struggle not to drop two shots,” he said.
"It was a good six but I played really well today and the round should have been in the 60s."
Rory McIlroy had an eagle on the eighth and birdie on the 18th in his round of 70 to lie two under, the same score as two-time winner Bernhard Langer after the 55 year old completed a second consecutive 71.
Overnight joint-leader Sergio Garcia was ten shots worse than his opening 66 to also finish two under, while American Dustin Johnson was the only player to reach seven under after 13 holes of his round, only to play the last five holes in six over par.
Defending champion Bubba Watson scraped into the weekend on four over after a 73.