Spieth in control at Augusta
Jordan Spieth carded the lowest halfway total in Masters history to take a massive step closer to a first major title at Augusta National on Friday.
Spieth added a second round of 66 to his opening 64 to post a total of 130, one shot better than the previous best set by Ray Floyd in 1976.
That also equalled the 36-hole record in any major - shared by Nick Faldo, Brandt Snedeker and Martin Kaymer - and at 14 under is the lowest 36-hole score in relation to par.
Faldo was 12 under on his way to winning the 1992 Open at Muirfield, with Snedeker and Kaymer 10 under at the 2012 Open and 2014 US Open respectively.
" It's cool. Any time you can set a record here is pretty awesome," said Spieth. "I'm very excited about today and the way I struck the ball. I struck it, I thought, better than yesterday and didn't rely on the breaks as much."
Spieth, who led by two shots after seven holes of the final round 12 months ago before finishing second to Bubba Watson, came into the week having finished first, second and second in his last three events.
And the 21-year-old has experience of winning tournaments by big margins after claiming the Australian Open by six shots in December and the Hero World Challenge by 10 a week later last December.
"I just need to keep my head down, set a goal for myself," the world number four added. "It's definitely going to be more challenging and I am going to have to be aware of that and be okay with a bogey or two.
"The hardest thing to do is put aside wanting to win so bad and just kind of going through the motions and letting my ball striking and putting happen.
"I got off to a great start and had a chance to win last year on Sunday. I'd like to have that same opportunity this year. Again, this is only the halfway point and I'm aware of that. W hat I learned (last year) was patience. The weekend of a major, those rounds can often seem like two rounds in kind of the mental stuff that's running through your head, the stress levels."
Spieth is just five months older than Tiger Woods was when he became the youngest Masters champion in 1997 and is playing at Augusta for only the second time.
" I got the awe factor out over six months before I even played the first time here," he explained. "To get here and to play rounds ahead of time; to play the golf course and after getting into contention last year and seeing what Sunday in the final group was like, now it feels more like a regular event.
"I think just having the experience of playing it a few times was all I needed to feel that way."
As the second round drew to a close, Spieth held a record-equalling five-shot lead over fellow American Charley Hoffman, who bogeyed the last to add a 68 to his opening 67.
Ernie Els was another four shots back after a disappointing 72 with Tiger Woods on two under after a 69, his first sub-70 score at Augusta since the final round in 2011.
"I have been there before but then again there's a pretty big separation between first and third which I didn't have back in 1997," Woods said of Spieth. "He has played beautifully, I played with him and Ben (Crenshaw) on the back nine on Wednesday and it was just a matter of continuing that and he has.
"Anything can happen here. You can play well and shoot over par, it's one of those courses that does that to you."
Els added: " Jordan is playing unbelievably well but we know how far there is to go. Front runners tend to do well here, but there have been some really good comebacks, so it's a big weekend ahead.
"I'd really like to shoot two 67s and see where that leaves me. That'd make me 15 under and that's about as good as a man can do.
"If it keeps blowing like this and the nerves get going... I don't want to wish badly on anyone but if he takes his foot off the gas or has a bad break here and there, it really gives you thought of catching him."
Rory McIlroy's bid to complete the career grand slam looked certain to end in disappointment, the world number one covering the front nine in 40 before a birdie on the 10th left him two over par and just inside the projected cut.