Imagine if Jordan Spieth knocks in this chip for a par. There would be riot. He doesn't but he gives it a good go, rolling up and over the hill to within six feet.

Birdie putt for Kuchar... over 20 minutes since his previous shot. His ball holds its line to the left of the can, knocking in for the par.

Kooch is the new leader...

Spieth drills in his fifth shot for a scarcely-believable bogey. How he didn't walk away with a snowman I don't know. Neither does he.

Rory McIlroy clumps his ball from the rough on 18, a tuft of grass leaps up and rests on the side of his face, prompting a swipe away. He has eyes for the ball only and knows he needs birdie. There aren't tweet tweets waiting in the bunker though I'm afraid.

What a bizarre round of golf we are watching.

Here's some pictures to sum up Spieth's 13th hole so far.

Image source, Reuters

Image source, PA

Image source, Reuters

Image source, Reuters

Right, they've decided where Spieth has to drop his ball. An army of photographers are stood, crouched, laid out behind him, fingers ready to click 10 to the dozen.

Spieth asks the spectators in front of him to move back "for their own safety".

The co-leader has a long iron in his hand, he's probably got about 200 yards to go. We can't tell you for sure. His caddie can't tell him for sure. Course planners don't factor in these sort of shenanigans.

Here he goes... shot number three for the American... he's cracked it just short of the green. A commendable effort all things considered.

While the rest of the Birkdale watches that Jordan Spieth's debacle, Brooks Koepka is still going about his business and makes birdie on the par-five 15th to move back to four under.

Elsewhere, Rafa Cabrera-Bello finds a greenside bunker at 17.

Jordan Spieth might be dragged into the television truck for a shift if he doesn't get a move on.

Here's what's happening: the place he should be dropping his ball is inbetween these two giant HGVs. Obviously, that ain't happening. So Spieth then has to move his ball for relief for line of sight.

Player and officials are still working out exactly where that is...

Spieth hit his tee shot about 20 minutes ago. Goodness knows what Kooch is up to. He might be having a quick nap.

Ross MacCallum: This has a Van de Velde feel about it..

Richard Hurren: I can't wait to hear what Peter Alliss has to say about THAT tee shot.

You'll be able to watch highlights at 20:00 BST Richard. Online and on BBC Two.

Jay Townsend
BBC Radio 5 live golf expert

Just a quick humorous quip - when Spieth's caddie Michael Greller was looking at his yardage book, he needed Google Earth!

I think the green is doable, but it's always going to be difficult to get the right lie.

Clubhouse leader Li Haotong is on the range. He's sensing play-off. At this rate, Jordan Spieth may well take a play-off if you offered it to him now.

Image source, Getty Images

Iain Carter
BBC Sport golf correspondent at Royal Birkdale

This getting evermore confusing. It looks like he may take a drop for an unplayable lie. He has gone 150 yards away from where the ball lay to take his penalty shot. That means he is taking his third shot here.

He is absolutely miles from the fairway, there is an enormous sand dune between him and the green. He will be completely blind.

Absolute bedlam on the 13th hole/practice ground. Jordan Spieth is currently stood between two television trucks, deep in deliberation with a couple of rules officials.

Spieth is gibbering like a man who is seriously panicking.

Spieth stands on the top of the steep dune, peering down the fairway to see Kuchar spank his approach onto the green.

What's Spieth going to do here? Plenty of head scratching. He's talking about an unplayable drop, apparently. That means he can drop within two club's length or go back on his line to the green.

The problem with option one is the lie won't be any better. The problem with option two is there are some television trucks in the way if he goes back towards the practice ground - which is the first place he can drop the ball and get a good lie.

Rafa's taken his sunglasses off. No need for shades when the Southport sky has clouded over in the late Sunday afternoon.

Fairway, green for the Spaniard but another two-putt to make par at 16.

He birdied both the 17th and 18th yesterday.

Errr, so Rory McIlroy just made eagle on 17 to reach five under. A birdie on 18 will tie the clubhouse lead. The way Jordan Spieth and Matt Kuchar are struggling.... who knows?

Image source, Getty Images

"Sit, sit" says Alex Noren on 18 as he chases the green in two on this par four. Over the back, he'll need up and down for par and pulls that feat off.

Branden Grace is also chasing eagle on 15 but the hook is disgraceful with his second. That ball path bent like a banana. He will have an up and down for birdie too but it's an outside chance at best from the rough.

Panic over. George has found Jordan Spieth's ball. Who's George? Dunno. But Spieth owes him a pint if he goes on to win this thing.

A courteous 'thank you' from the Texan, who then has to scamper up the mound in front of him to see where he's going.

Spieth is 120 yards right of the middle of the fairway. 120 yards!

Golf website Skratch, external have already applied Matt Kuchar's real name to the Claret Jug...

Image source, .