Oliver Wilson
Former Ryder Cup player on BBC Radio 5 Live at Portrush

It's not normal to run away with a tournament - there's an element of doubt whether Harman will carry on, but with the way he won last time there'll be slight concern from players looking at the leaderboard.

That being said, there's still a long way to go.

Weather will change and links golf definitely lasts longer.

As we've seen with Justin Rose, things can change in a hole.

Tommy Fleetwood manages to save par as he two-putts himself out a tricky one. Rory McIlroy's birdie bid comes up just short and he taps in to stay at one under.

Iain Carter
BBC golf correspondent on BBC Radio 5 Live at Royal Portrush

All that hard work from Justin Rose has just disappeared in one hole - untidy stuff after having been so tidy beforehand.

That's a damaging hole for Justin Rose, who takes seven on the par-four 11th to drop back to level par.

He'd not registered a bogey in his first 23 holes of his tournament, but that run ended at the sixth.

There are three par-five holes at Royal Portrush. All three of them are big birdie chances, particularly on benign days like we're currently enjoying.

But Tyrrell Hatton has been unable to take advantage today. He found a fairway bunker off the tee, which stopped any thoughts of chasing the green in two. In the end, it was a good two-putt from 45 feet to save par.

A rollercoaster back nine for Rasmus Hojgaard. After back-to-back birdies Hojgaard makes consecutive bogeys. However, he stops the slide down the leaderboard with a much-needed putt for par at the 16th.

Two years ago, Brian Harman came from nowhere on the Friday at Royal Hoylake.

He carded a six-under-par round on the second day to seize control of the tournament and that's how he stayed, eventually winning by six shots.

The Georgian looks rock solid today and oh look, he's five under for his round.

Another Brian Harman birdie! His fifth of the day comes on the par-three 13th from about 15 feet.

The American left-hander moves two shots clear of the rest.

Tommy Fleetwood stares at the ground in frustration after he finds the rough on the edge of the 10th with an errant approach shot. The Englishman started well today but a few errors have crept in over the past few holes.

Rory McIlroy is on the money as he finds the green and gives himself a reasonable birdie chance

Another big birdie opportunity for Harris English at to close out his front nine.

It's almost 40 feet and he does drag it six past the hole. Nerveless coming back though to save par.

He'll make the turn one off the lead.

"Small margins" is quite the cliche in professional sport now.

Couldn't get much smaller here for Justin Thomas' putt earlier on.

Surely it's going to drop. Surely...

Justin Rose will have to play that provisional ball from the fairway - and this one goes right too, into the rough beside the green.

The Englishman staring at least a double bogey in the face here and he needs to make sure it's not any more than that.

Trouble for Justin Rose off the 11th tee. He's gone right and into a very dense section of bushes. You'll struggle to find that in three days, let alone three minutes - even though the whole of Northern Ireland appears to be looking for it!

He knocked a provisional onto the fairway before joining the search for his original ball.

Oliver Wilson
Former Ryder Cup player on BBC Radio 5 Live at Portrush

At the turn, Oli Wilson offered some insight into whether Rory McIlroy's swing is down to mechanics or brute strength:

It’s speed. You have to have good mechanics for it to operate as efficiently as it does. He hits the middle of the club face so much that when you have that you are able to switch it on a little bit.

But he’s been fast since he was a kid. When he first came out on tour, I remember he had the speed then but he was having some back issues so he developed the strength to cope with the speed and it’s just been a gentle progression throughout his career to the point where he plays golf how we all want to.

It just looks so effortless and fluid. He takes on every shot that the golf course asks and executes it most of the time and that’s what makes it so much fun to watch.

You can’t dial Rory back. You have to accept there’s going to be mistakes because he has all the power, all the shots to take on, and he wants to take it on and show how good he is.

Rory McIlroy is left with a huge putt for a birdie on the ninth but his radar for the hole is slightly off and the ball curls away. The crowd surrounding the tee raise the noise when Tommy Fleetwood gets even closer to sinking a monster putt.

Both men have easy tap-ins for par.

Brian Harman slides his birdie putt left and, on the easiest hole on the golf course, the leader of the Open has to make do with par.

Image source, Getty Images

The least heralded of the five overnight leaders was probably China's Haotong Li.

He's just got under way and fared rather better than Jacob Skov Olesen down the first.

On the green safely in two and then comfortably home for par.

So many snails emerged onto the pavements in my neighbourhood when the storms rolled in this week.

At least I've now got some good options to name them.

Name that Snail - you guys are inspired!

That familiar waggle of the club and the several looks at the target area before Brian Harman strikes his third shot at the par-five 12th...

He leaves his pitch from just off the green about 12 feet short. Although he'll have a putt for a birdie and a two-shot lead, he perhaps should have been a tad closer than that.