Tom Fordyce
Chief sports writer at Royal Birkdale

Rain blowing in on the wind now, the galleries head down as they stride through the wet grass to keep pace with this Spieth v Kuchar showdown. Is this the Fizzle In the Drizzle or The Squeak in Dreich*?

* Ed note - I didn't know what 'dreich' meant either, so I had a look. It means dreary/bleak, in relation to weather.

Hold on... apparently they haven't found Spieth's ball yet. One has been dug out by the eager spectators but that looks like it has been there since 1986.

He might be doing the walk of shame back to the tee...

Iain Carter
BBC Sport golf correspondent at Royal Birkdale

It is getting ever more ragged off the tee for Spieth. Matt Kuchar is in the rough to the right-hand side, but nowhere near into the rough as Spieth.

We can see a knott of spectators around the ball,it doesn't look like a search party, it looks like they have found it, but it looks very rough terrain.

Jordan Spieth touches his temples with his fingertips. His drive on the 13th has more slice than a refreshing G'n'T. His ball starts off on the line he wants, then drifts off right like an enthusiastic labrador being taken away from the park by its owner.

He's over the crowd and into the thick, untrampelled rough. Someone brings the shears.

-8 Spieth (12), Kuchar (12)

-6 Li (18)

-4 Southgate (18), Leishman (18), Noren (17) Cabrera-Bello (15), Grace (14)

Selected: -3 Casey (18), McIlroy (16); -2 Z Johnson (18), Wood (18), Stenson (14)

Full leaderboard available here.

A colleague references Rory McIlroy's body language and a quick image search shows many photos of this exact face today. Lips sucked in, an anger underneath. The sand welcomes him on 16, just right of the green. That will cheer him up no end...

Image source, PA

Rafa Cabrera-Bello misses a birdie chance at 15. The par-five has yielded plenty of reward this weekend, but not for the Spaniard as he shoots wide of the mark from eight feet.

It's an easy par putt, but he's running out of room to make ground on those above him.

Kuchar goes first, down the hill, a slight left to right. His line is good, his speed not so, leaving a tester of a putt.

Spieth comes in from about 25 degrees to the right.. same result.

These tiddlers are the sort you just walk up to and tap in on day one. On day four you think about them a bit more. Kooch trots up and plants in his par. Spieth studies his line from all angles, then cans it.

Bunker alert. No surprise it's Brooks Koepka in the sand behind the green.

Austin Connelly has to use all of his 5ft 7in frame to hack his way out of another bunker. Between them, they could write a guide to Birkdale's best beaches.

Koepka dropped shots in both his previous rounds here - he could be about to do the same.

Faced with a tricky lie close to the bank, it's a clever shot from the American to clip out close to the flag. But that's not enough to par. It's a dropped shot for Koepka.

Connelly can't rescue this one either - he double bogeys.

Jordan Spieth has been a golfing James Bond so far today. Finding himself in a dangerous situations but somehow wriggling his way out of too much bother, a couple of scratches aside.

On the 12th tee, looking ahead to a short par three with a slight downwind, both players instruct their balls to "sit softly". They listen. Both men reach for the putters....

Image source, EPA

Branden Grace on 14, par three, 200 yards. Starts it right, draws it in, takes a skip forward on the green and settles 15ft from the cup. A look at birdie...

Alex Noren is hunting eagle on 17, second shot is getting the full timber. Huge swing, hard swing, starts right and stays there. His third on this par five will have to come over a bunker and into a small landing zone before the flag.

Jay Townsend
BBC Radio 5 live golf expert

This is a tale of two different putters. Kuchar has the feel of the putter at the moment, while Spieth doesn't.

With the windy, blustery conditions, this is not a good time to be suspect with your putter.

The crowd horseshoe around Spieth's ball, the American looking down on the 11th green. An open stance, an open club face, he wants to dink this onto the bottom of the slope and run it up to the hole. Pretty good. Although his putter - usually his most potent weapon - has not been firing.

Kuchar runs his birdie putt up the hill, ball arcing round right to left before waiting outside the door. He knocks in, leaving Spieth with a question to answer. No problem.

On we go. Now it is a seven-hole shootout...

If anyone isn't an 80s child and doesn't know what silly string is, here is Tom Hanks giving a good demonstration in the classic film Big.

Image source, Rex Features

Holes are running out for Branden Grace who bumps one out of the rough on 13 to leave 40ft for birdie. Rory McIlroy stands over shot number five on 15 from the bunker, big sweep of sand, big shot. Leaves a club length for his bogey. A first bruise on his card. You don't see too many pros lose a ball on a hole. I think my record is around four.

There's an outside birdie chance for Rafa Cabrera-Bello, who needs to make a few of these if he's to climb any further up the leaderboard.

It runs just by the flag, but he takes par with a simple putt on the par three to stay at four under.

Two par fives to come in the final four holes - room to make moves.

Iain Carter
BBC Sport golf correspondent at Royal Birkdale

It has been a very stressful round of golf for Jordan Spieth.

You could get a tape measure out between the ball of co-leaders Matt Kuchar and Jordan Spieth on the 11th fairway.

Kuchar, trouser legs flapping in the increasing wind, to go first... he's muttering... not sure why because his ball is on the green. A long way away but on the green nonetheless.

That shot looks even better a few seconds later - because Spieth has sprayed his into the crowd on the left side of the green.

"Hit it fat," moans the Texan.

Brooks Koepka's tee shot at the par-three 12th leaves him with a lot of work to do if he's to make birdie.

He's on the edge of the green, but might need to call a taxi to reach the flag. It's a long, uphill putt that rocks up just beside the cup. Par.

Austin Connelly goes one better. He sticks his approach to within putting distance and cards his second birdie in as many holes - if it wasn't for that awful run of four bogeys on the front nine the youngster would be in a strong position.

Tom Fordyce
Chief sports writer at Royal Birkdale

Spieth, who appeared to be on cruise control across the first three days, now has his hazard lights on and is veering out of his lane. Whether Kuchar can overtake him on this back nine is another matter - the prospect of an Open win has lain heavy on the shoulders of all the big contenders this afternoon