We said the tee shot at the first showed no nerves from co-leader Mackenzie Hughes.

His second did. Overshoots the green and faces a tough up and down out of the rough to save par.

Louis Oosthuizen locates the green, albeit his birdie putt will be a monster. Par, most likely.

"Yeah I like it," says McIlroy after his tee shot on the par-two second.

And so he should. It's in prime position to challenge for a birdie, looking straight at the flag with 70 yards to go.

Jon Rahm steers home the par putt to stay at four under after three.

From where he was, deep in the rough after his tee shot on the par three, that might well be the save of the tournament. Golden Glove if this was Euro 2020.

And Russell Henley loses his share of the lead for the first time since Friday. Just the two leaders now in Louis Oostuizen and Mackenzie Hughes.

He can't cover the 30ft to the hole and has to two-putt for a five.

Rory McIlroy gets his par. With the exception of the dodgy tee shot, he's looking strong.

Bryson DeChambeau's driving radar is a little off again on the second. He bombs one down the right and into the rough.

He's got 60 yards or so to gouge his ball out and up to the green, although he's on the wrong side to really attack the pin.

He ends up hacking out short of the green and knocks his third up to four feet. Par.

We're not seeing anything of Scottie Scheffler, but he too is in for par.

If the opening tee shots are anything to go by, there are no butterflies in the tummies of Louis Oosthuizen or Mackenzie Hughes.

Straight down the middle. Good starts.

Jon Rahm not only avoided the penalty area after that poor tee shot on three - he might rescue par.

A salvaging shot that had to be seen to be believed.

The pin was so close to the edge of the green he was pitching from, it seemed impossible to hold the ball.

When he swung his club, I thought it would end up in the rough on the opposite side. But it rises, comes down quickly and stops dead within 10 feet of the pin. Sublime.

Delightful from Rory. After shooting into a bunker off the tee, he's in a great position to make par with an excellent putt.

Not so for Russell Henley, whose third shot out of a greenside bunker overshoots the hole by about 30ft.

Image source, Getty Images

Our final group on the final day features a couple of players with contrasting experiences at golf's Majors.

Louis Oosthuizen has been there, seen it, done it and got the T-shirt, winning The Open at St Andrews in 2010 and registering eight other top-10 Major finishes, including five as runner-up.

Mackenzie Hughes, meanwhile, has missed the cut in six of the eight Majors he's played - his highest finish tied 40th at this year's Masters.

It's a whole new ball game for the Canadian.

Only two men left to tee off tonight then...

Impossible to truly master this game of golf.

Jon Rahm, having started so well with successive birdies, pulls his tee shot well wide on the third and it flies off the bank into deep rough.

Might even be in out-of-bounds territory. Rahm looks disgusted with himself.

Well, well, well.

Co-leader Russell Henley goes straight from the rough to a bunker on the first. There's going to be work to do for a par now. Can he feel the chasing pack snapping at his heels?

Rory McIlroy's second shot lands next to a sprinkler at the front of the green, meaning he might get a drop. Not too bad.

With three players tied for the lead at the start of the final round, you may be wondering what happens if two - or more - finish up level at the end of play.

Well, things have changed in recent years.

The US Open used to have an 18-hole play-off which meant the contenders had to come back on Monday to play the entire course again.

That was the case the last time the tournament was held at Torrey Pines, when Tiger Woods saw off Rocco Mediate in 2008 - which, coincidentally, was the last time the event actually went to a play-off.

Now, though, it comes to a play-off over two holes, the seventh and 18th, straight after the final round. If players are tied, we then go to sudden death over a loop of the seventh, eighth and 18th.

Scottie Scheffler plays a 3/10 chip up the first green, his ball finishing a good 20 feet short of the hole.

What can Bryson DeChambeau do from 25 feet with the flatstick in hand? On Saturday, he may have been bogey-free but he probably left five birdies out on the course with tentative putting. And he's started in the same fashion today. A foot short. Par.

Scheffler for his par... nope. Shot gone.

What an approach from Jon Rahm at the second hole, to within three feet of the pin.

A straightforward birdie for the Spaniard from there.

He looks cool as a cucumber, which isn't always the case.

Just one shot off the lead. Wow, what a start.

Here we go then.

Rory McIlroy squints to follow his opening drive. It's gone right and into the bunker, on a slight upslope but not a disaster.

Russell Henley goes in the same direction, but doesn't make it to the bunker and is instead in the rough.

It's a steady rather than stellar start, but that's ok.

Ian Poulter made an early birdie but followed it with a bogey soon after.

No bother, though - he curls in a tidy putt on the fifth for another birdie and back to one under.

He'll need to be bogey-free from now on to contend though, surely.

Scottie Scheffler pumps his ball out of the rough. He is down the left, so has a clear sight of the flag but doesn't give it enough of a whack, the ball coming up just short of the green.

Bryson DeChambeau, from 20 yards further forward in the sand, sends his approach pin-high, 25 feet to the left. Safe option. No need to go chasing pins at this stage.

Italy's Guido Migliozzi reaches the turn on two under for the day and one under for the tournament after his second Sunday birdie.

Migliozzi finished runner-up in the play-off to US Open halfway leader Richard Bland at the British Masters.

But while Bland has faded here, Migliozzi remains in top-10 contention.

I'm sure Rory McIlroy is walking more confidently than normal as he makes his way to the first tee to shouts of "come on Rory".

It's almost time...