Smith has 192 to the pin on 16.

He looks a bit anxious as he sends it on its way. Oooooh, it creeps up the hill onto the same level as the pin and that's another birdie putt for the Australian.

A ball-striking clinic from the Players champion so far.

Image source, Getty Images

Jordan Spieth misses a short birdie putt on 18 and that kind of sums up his tournament and his round today - a story of missed chances.

Spieth has given himself plenty of looks with some wonderful iron shots but the putter just hasn't been as hot as it needed to be to challenge.

Still a solid Open performance though.

What's happening in the final pairing?

Both McIlroy and Hovland have gone left and are in the rough.

"Gouge-time," is how one television commentator describes it.

Graeme Storm
Two-time European Tour winner on BBC Radio 5 live

The pressure is just starting to build on McIlroy and he's looking like he feels it is trying to run away with him.

Smith and Young find the fairway at 16.

This is so tense.

Alex Bysouth
BBC Sport at St Andrews

There’s been a shift in the tempo of the cheers from the crowd following Rory McIlroy - when he pulled clear fans on the Old Course were almost giddy with excitement, now there’s an anxious croak in their shouts, claps of encouragement rather than the buoyant confidence in their boisterous support earlier.

-19 Cameron Smith (15)

-18 Rory McIlroy (14)

-17 Cameron Young (15)

-15 Viktor Hovland (14),

-14Dustin Johnson (16)

-12 Brian Harman (66), Tommy Fleetwood (16)

Full leaderboard

No mistake from five feet. Smith's run of birdies comes to an end but he saves an important par at 15 and he's three from home.

Young missed a golden chance for a birdie, though, so he remains two back.

Fair play, Graeme Storm called it. That's why he earns the big money.

The up and down was harder than we first envisaged, with McIlroy's putt stopping on the top side.

Fine, fine margins.

We never thought we'd be saying this an hour or so ago, but who wins The Open now, Cam Smith or Rory McIlroy?

Thumbs up for Smith - thumbs down for McIlroy.

Image source, Getty Images

Smith, for a SIXTH birdie in a row.

He starts it well outside the left but doesn't get enough purchase on it and that's the first tentative putt I've seen from him today.

Oh the ebbs and flows of major championship golf.

Now, we're not saying Rory McIlroy must go up and down from here but... if he doesn't then the engraver might just start practicing outlining his Cs.

For Cameron, obviously.

McIlroy negotiates the slopes well with his wedge but the relative silence indicates that he still has work left to do.

Cameron Young!

The American, after a monster drive on 15, clips a nice little wedge in and gets it to check on the second bounce.

That's no more than 10 feet to tie McIlroy for second.

Smith's got lucky with his drive at the 15th.

Woosh! He watches it closely. Not so close this time but he's safely aboard the green, about 35-40 feet short.

With the way he's been putting today, I wouldn't put that one past him...

Alex Bysouth
BBC Sport at St Andrews

Finally a more comforting tune for Rory McIlroy’s ears, the sound of Cam Smith screaming “fore right” after his drive at 15.

Graeme Storm
Two-time European Tour winner on BBC Radio 5 live

Image source, Getty Images

McIlroy really has to make the birdie on the 14th but I think that was the wrong club choice. Really difficult to up and down it from where he is.

A par save from the road - that's Jordan Spieth in a nutshell.

A birdie down the last to share the clubhouse lead for Spieth, who has served up a little bit of everything this week.

When the going gets tough, will McIlroy get going?

For the first time today, the Northern Irishman is chasing. Can he still stay in his bubble even with all this madness going on around him?

The early signs are yes. He lamps a drive on the par-five 14th down the middle and knocks his second close to the green.

Looks to be a decent chance of a birdie, despite being a tricky knock on.

Alex Bysouth
BBC Sport at St Andrews

One lad behind me has his fingers out trying to count how many birdies in a row that is for Cam Smith…

The Australian can now see St Andrews town on the horizon as he stands over his tee shot at 15 - the Claret Jug is down there somewhere if you look really, really hard.

Cam Smith finally misses a shot. He leaks his drive on the 15th to the right, but he looks to have nestled in a nice fluffy lie.

The better you play, the luckier you get...