Smith has 187 yards into the 13th. Tough to get it all the way back to this pin.

Oh he likes it. It's another cracker - an uphill putt of around 15 feet for yet another birdie, and that one's to tie for the lead.

Young sticks his in tight as well! This pairing is producing some lovely golf and they're really putting the squeeze on Rory behind them.

This is a critical period in the race for the Claret Jug, folks.

Viktor Hovland goes first on 12, bumping up the slope in front of the green and stopping his ball close.

That's how you use the contours. A first birdie of the day looks to be incoming...

What can McIlroy muster? Something very similar! His ball also nestles on the flat bit of the green which surrounds the hole.

Excellent birdie chances here for both men.

Dennis Ethan: This is where Rory McIlroy has to earn the major, how does he counter the pressure from Cameron Smith?

Image source, Getty Images

Another characteristic of Jordan Spieth is his mental strength, and as usual he's hit back from a bad bogey to get another birdie at 15 and get back to 12 under.

He's not done just yet - Sam Burns birdied the last four holes this morning, and if Spieth does that it'll be interesting to say the least!

John Murray
Commentator on BBC Radio 5 Live

More Australian cheers here. Once again Cam Smith is right there, saying to Rory McIlroy 'just you keep an eye on me.'

Three birdies in a row. No question - he is the big main challenger to Rory McIlroy's lead.

Cameron Smith has reached the 13th, which is where he recklessly frittered away two shots yesterday after attempting a miraculous recovery from a fairway bunker.

He'll have no such adventure this time. In the fairway and lookin' good.

Young's hit a beauty too, by the way.

The short par-four 12th has been driveable this week, but probably not today with a slight headwind fluttering the eyebrows of the world's best golfers.

McIlroy has been knocking stripes off his ball from the tee and does so again, sailing over the bunkers and leaving him with a short wedge in.

With Smith coming up on the rails, it's starting to feel like McIlroy will need to drop a gear here and accelerate in pursuit of a birdie.

American Brian Harman, he of the putter head the size of a phonebook, has gone birdie-birdie on 15 and 16 to get to 12 under and as he's slightly ahead he could set the clubhouse target the way he's going.

Classic McIlroy.

Hits the 11th green, lags a putt, tidies up for par.

Hovland has to do more than that now, however.

Off the tee is good, but still doesn't give him a proper look at a birdie.

Alex Bysouth
BBC Sport at St Andrews

It’s a strange sensation, watching the venue clear out after the final group passes through - grandstands that were rocking and roaring one minute suddenly deserted as the leaders disappear over the horizon.

Not that Rory McIlroy or Viktor Hovland will notice, the flood of fans is flowing alongside them.

Another one! Cam Smith's birdie try at the 12th looks to be sneaking off to the left but it catches a piece of the hole and the ball drops!

Five under for the day and with a red-hot putter in tow, the Australian looks determined to take this away from McIlroy.

Cam Young's on the move early as he sends another long putt on its way. That's nowhere near strong enough, and the New Yorker will have a tester for par, which he makes!

He remains three back and still in it, but Smith's the one putting the wind up Rory.

Massive misjudgement from Cameron Young at the 12th, coming up woefully short with his second at the short par-four.

"No way," he says. Yes way, I'm afraid.

Smith's whopper of a drive sneaked onto the front of the green, but this one requires all of his attention.

The Australian lets out an annoyed grunt as he comes up 12 feet short. Still a birdie chance though.

Iain Carter
BBC golf correspondent on Radio 5 Live

Rory has that bounce in his step and has just tapped the accelerator.

Image source, Getty Images

That's a save and a half from the Hov.

Can that finally light his fire?

Alex Bysouth
BBC Sport at St Andrews

A concerning chorus of “ooohs” for Viktor Hovland greet his second shot, followed by rapturous cheers and more chanting for Rory McIlroy with his mammoth putt.

For a moment the crowd here thought he was about to repeat yesterday’s trick and eagle the 10th.

McIlroy was already eyeing up the 11th from the tee box as Hovland scrambled with his par putt.

The Old Course fell completely silent for a moment there…

Only the 125 feet separating Rory McIlroy and an eagle. Most of us would need a wedge from here...

What a shot! What judgement! McIlroy punches the post code into his putter and it arrives just outside its destination.

Tweet-tweet! Another birdie is assured.

McIlroy leads by two again. Eight left to play. Eek!

Roars ring in Hovland's ears just before he duffs his second shot on 10.

The cheers were greeting Smith's birdie up in front and may or may not have got inside Hovland's head.

Iain Carter
BBC golf correspondent on Radio 5 Live

Hovland has been playing more conservatively but he might have to start thinking of going things now. Time is ticking.

Image source, Getty Images

Cameron Smith walks another birdie putt in, converting a 16-footer for a tidy two at the 11th.

The Players champion is well and truly up for the challenge today.

Four under for the day.

Image source, Getty Images

Jordan Spieth in bother now after finding a devilish bunker short of the 14th green - he comes out sideways to leave himself a chip up the green, then chunks it pretty much like me or you would do on this tight links turf!