Image source, Getty Images

The romantic challenge of Fred Couples may have just come to a watery end. He's swimming on 11. Is this the start of something from Jonas Blixt? Testing putt for birdie holed on eight, he's back to four under and four off the pace. Spieth, from the eighth fairway, is way right, while Bubba is unlucky to skip off the green and down the slope at the back.

Ken Brown
BBC Sport commentator

"Yes, Bubba's unlikely to intimidate him. He's more likely to give him a hug."

Andrew Cotter
BBC Sport commentator

"Look at the distance between the drives of Jordan Spieth and Bubba Watson. They are playing together you know. I'm not sure there's a better playing partner for Spieth than Watson."

As Spieth prepares for his second, Watson is so far ahead that he is merely a fleck on the horizon. The chasing pack remain at arms' length, Matt Kuchar on four under, Rickie Fowler and Jonas Blixt another shot back.

Ken Brown
BBC Sport commentator

"Oh my goodness. He's mullered that. It's 315 yards to clear the bunker there and it was still taking off as it went over the trap."

When Bubba Watson drives, he has the feet of Chris Gayle. Front foot out of the way, try to hit the spinner over the boundary. His big-stick shot at this par-five has gone into another state, an absolute monster. As he and Spieth head down the fairway, they chat away, very friendly. Can you imagine Tiger and Faldo doing that on the final afternoon at the Masters?

Image source, AP

Par five, 570 yards

An uphill hole, that demands an accurate drive in order to avoid the right-hand side fairway bunker. Mounds on the front left are the only protection for the long, narrow, bunkerless green. Australia's Bruce Devlin scored the second albatross in Masters history here in 1967.

2013 average: 4.68 Rank: 17

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A frustrated Rory McIlroy has bogeyed 15 to go back to one over. Who said he was coming from nowhere? Fred Couples begins the back nine with a bogey at 10, two under. Am I right, is it now only about Spieth and Watson? If not, who can stop them? They are on the eighth tee.

Jay Townsend
BBC Radio 5 live summariser

It's too early to say only 10 left to play. There's a lot of golf left out there. The important thing is Spieth has to stay in the moment. It's the tee shot now. That putt has gone. It's cliché and sounds terrible but that's how you do it.

Ken Brown
BBC Sport commentator

"Another gem, nerveless. It takes such guts to do that."

Image source, Reuters

Spieth for birdie...eight feet downhill...skidding down a slope of ice, rapid. Barely touches it, rolling, rolling, and dropping! A fourth birdie in the first seven from Spieth, he goes to eight under to lead by two after Watson's decent par save. You feel the rest are just the supporting cast for this duel.

Ken Brown
BBC Sport commentator

"How the ball came out like that, that soft, when the ball was plugged, is simply stunning. In fact, stellar."

Spieth and Watson are a two-man highlight reel. Seemingly in trouble in the greenside sand on seven, Watson displays the touch of a pickpocket to flop the ball out and then persuade it to the use the slope back towards the flag. He should save par.

Bubba Watson looks to the sky, baffled by the breeze after dumping his second shot at the seventh into the sand. "The flag is straight south," says Spieth as he prepares. Silence punctured by a plane flying overhead, he sends his second right over the flag, eight feet away. This is turning into the Jordan Spieth show. Remember, no debutant has won since 1979, no one has ever won at a younger age.

Ken Brown
BBC Sport commentator

Ken Brown has been answering your questions on the BBC Sport Facebook page., external Go there to read all his replies, but here are a selection of his thoughts:

If a 16 handicap golfer turned up at Augusta to play off the Masters tees, what would you expect them to shoot?

I think if they broke 100, they would do very well, especially with these pins. It is quite manageable tee to green, but once you get on the green it is extremely tough.

What would you do to speed up play?

The easiest way would be to make courses shorter and easier and remove all rough! A really good golf course doesn't actually need any rough.

What is your favourite course and hole?

My favourite is the Old Course at St Andrews and my favourite hole is the 12th at Augusta. It is a pretty hole and just a short iron but you have to be so precise.

Az: Good call on the chips with curry comment. Equally, if you do not order rice with a curry, then you are no friend of mine.

Rory on 14, following up that bogey six at the 13th. 12-footer for birdie, the world number nine bends his knees as the balls drops in. If only he hadn't found water, the charge may still be on.

There was so many players in contention when we began the day, but Spieth and Watson are putting daylight between themselves and the rest. Spieth at seven under, Watson a shot back. Can they keep the advantage? Who can bolt from the pack and challenge? Jonas Blixt had played par golf up to seven, but a long par putt slides by. He's back to threes.

ESPN's Justin Ray, external with another belting stat: "Long way to go. Each of the last 5 Masters winners played holes 13 through 18 on Sunday in -3 or better."

Birdie for Bubba on sixth. From the edge of the green he gives it slightest of tickles, allowing gravity to do the rest with a final plop into the cup. Momentarily he's level with Spieth, but the youngster is instantly regaining his one-shot lead thanks to that wonderful tee shot.