Tony Finau posts the lowest score to make it back to the clubhouse. His early alarm clock didn't hamper him too much as he ends the day level par, four under for the tournament.

Finau's approach sums up the changing elements. He averaged 330 yards off the tee on Thursday and just 284 today. The big dog not being ripped as often.

Image source, Getty Images

To me, Andrew Johnston has the look of a man who would make a cracking WWE character. Size, stature, he'd be good on the microphone. He could use a golf club as his weapon of choice.

What do you think?

The Beef has made a triple-bogey on 11, taking him back to one under.

Andrew Sullivan also carded a triple earlier and drops to even. All of the above (apart from the WWE stuff) means Justin Rose is the top Englishman on three under. He starts at 14:04 BST.

Zach Johnson reaches for his wedge on the eighth tee and guides one towards the pin.

The Postage Stamp has proved profitable this morning and it's another birdie chance for the 2015 Open winner.

Phil Mickelson is having another magnificent round. Watch this fine approach chip on the seventh.

Henrik Stenson strides away, broad shoulders carrying the stresses of major tournament golf. He has another birdie courtesy of a rock-solid putt on seven. That moves him second on his own, four behind Lefty.

Zach Johnson appears to have his eye in, he's driving an average of 279 yards so far today.

Cap donned, glass on, the American shows little emotion as he lands another approach on the green, though - still work to be done.

His birdie attempt falls slightly left, but it's another par for the 40-year-old.

Image source, .

Hole-in-one camera takes us to Martin Kaymer this time. These players are treating this like a teddy bear machine in an arcade, many are gripping the bear and getting it close to the bucket but just missing out.

Kaymer wedges one into the postage stamp, left of the flag, back spin, whips towards the hole, three inches wide. Tap-in birdie.

Ben Dirs
BBC Sport at Royal Troon

The weather in Troon has officially got interesting. The rain not torrential but persistent, and it's muggy out there, the kind of conditions that will have you sweating under your waterproofs. 

Having almost witnessed Mickelson make history on Thursday, he's continuing to make the Old Course look like a municipal pitch and putt. 

His tee shot at the Postage Stamp, six inches from an ace, was a thing of beauty.

Casey walked off with a seven. He is nine over for the tournament and probably cannot wait to get out of Troon.

A crowd of brolly-wielding supporters greet Phil Mickelson on the 10th tee and he fires one through the rain slightly left of the fairway.

It's a difficult par four, especially with today's weather, but Mickelson negotiates his way on to the green and makes a welcome par.

Eight still to play today, but he's yet to drop a shot.

Martin Kaymer cannot make his birdie on seven but him, Soren Kjeldsen, Henrik Stenson and Andrew Sullivan are ensuring some European flags are beginning to mingle on the leaderboard.

Image source, BBC Sport

Yep. That's no problem for Johnson, he makes that putt look simple.

It's his third birdie of the morning, and moves the American to six under.

Out from under the umbrella, swing, back under the umbrella quickly.

Henrik Stenson first on the sixth, good solid iron, though he's not overly pleased. It leaves a long birdie putt which narrowly misses.

He's six under, Martin Kaymer is five under but goes hunting the green on seven. Terrific iron, over the flag, good grip on it, opens up a birdie chance.

Keegan Bradley looks like he will reach six under too. The par five fourth is just getting hammered and Bradley has a few feet left to pick up another stroke and move second.

-11: Mickelson (9)

-6: Kjeldsen (12), Stenson (5)

-5: Kaymer (6), Z Johnson (5), Keegan (3), Reed (13:04)

-4: Johnston (9), Pieters (3), Cabrera-Bello (2), Thomas (12:53), Stricker (14:15), Horschel (15:10)

Selected others:

-3: Garcia (3), Rose (14:04)

-2: D Johnson (6), Fowler (14:26), McIlroy (14:37)

-1: B Watson (14:37)

E: Spieth (14:04), Willett (14:26)

+1: Westwood

+2: Day (14:26)

Tee times and full leaderboard, external

Zach Johnson reaches the green in three and may fancy his chances of a birdie as he closes in on the pin.

The defending champion dropped a shot at the last, but looks solid on the fifth - he's ground to make up on the leader, mind.

A warning from Ken...

"These opening nine holes are critical but that back nine that's going to be tricky if the wind's in the wrong direction."

As Phil Mickelson heads for the back nine, he'd be wise to get his head even more on than it already is.

Watch Zach Johnson's delightful chip on the second for a birdie. It has been a positive morning so far for the American but he has a lot of ground to close the gap on Phil Mickelson.

Andrew Johnston, seemingly loved as much in LA as he is in London thesedays such is the breadth of his golfing fame, has done really well to card four birdies on the front nine and cancel out a couple of dropped shots.

He turns at four under, seven off the pace. He's finding the fairway a lot - 86% of the time - and that's underpinning his game.

Image source, PA