Righto, that's us for the night. Night.
- Leaders: -13 McIlroy; -12 Wiesberger; -11 Fowler; -10 Mickelson, Day
- -9 Oosthuizen, Ilonen, Stenson, Palmer
- -8 Donaldson, DeLaet, Stricker
- -7 Westwood, Chappell, Mahan, Scott, Furyk, Luiten
Rory McIlroy on his round of 67: "It really was a gutsy performance. I felt like every time I made a birdie I made a bogey. But I'm really happy with how I finished again, it was really strong and it puts me in a great position.
"I knew there were guys ahead of me making birdies and it gives me a lot of confidence knowing that if I get challenged and people put the pressure on I am able to respond like I did today. If I can keep playing well and staying mentally strong, there is another major to maybe come my way."
Rickie Fowler, -11 and two off the lead: "That was a good, clean, solid Saturday. I had a good sense of the speed today on the greens and I felt in control of the swing. It'll be fun tomorrow."
Former European Tour golfer on BBC Radio 5 live
McIlroy is the class of the field. We've said several times this week he should win. If he plays well he should win. If he plays his best he should win by five or six.
There are only three par fives on this Valhalla course and they will likely prove vital in deciding who lands the bounty.
Rory McIlroy is six under par for his nine attempts so far. Bern Wiesberger is level par for the par five drags and Rickie fowler is -7.
That was some day's golf - and tomorrow promises to be an absolute ripsnorter. There are 18 players within six shots of the lead, there will be bullets flying all over the place tomorrow until there is one man standing. McIlroy and Wiesberger will be the final group out, with Fowler and Mickelson up ahead of them. Europeans in the mix, other than the leading two, are Nordic pair Henrik Stenson and Mikko Ilonen (-9), Wales' Jamie Donaldson (-8) and England's Lee Westwood (-7).
Former European Tour golfer on BBC Radio 5 live
That was Tiger-esque from Rory. He didn't play that well and he's got a one-shot lead.
McIlroy to putt first - IN! That's the outright lead heading into the final day, courtesy of a round of 67. The Northern Irishman is one ahead of Austria's Bernd Wiesberger, with whom he'll play on Sunday. Day prods his birdie putt home, moves to -10 courtesy of a round of 69.
Bernd Wiesberger reacts to his round of 65: "It's huge. I felt really well out there, really calm and I hit a great tee shot on the first which calmed the nerves. I'm really proud of how I put myself into this competition. I know I belong out there with the guys and can compete."
Wiesberger carded three successive birdies to close and finish on 12 under.
The most remarkable part about Wiesberger's performance so far this week is that his birdie at 18 today was his first on the par fives. Here's McIlroy from the sand and he's got a makeable birdie putt. Day's escape is a touch closer, both have six or seven footers for birdie...
Day finds the bunker front right with his second at 18, here's Rory... same again, but they've both got plenty of green to work with.
Here's Palmer with that saver and it's a doozy, the man from Amarillo is in with a 69 for nine under par and a tie for fifth. Furyk makes par at the last for a disappointing 72 and seven under overall, he got a bit creaky down the stretch.
It's all gone wrong for Ryan Palmer on 18 - he muffs his first chip from the fluff, meaning he's still got plenty of work to do to save par. Here he is again... races it seven feet past, got a knee-knocker for par....
Austrian Bernd Wiesberger, with no major pedigree to speak of, has two second-place finishes in 2014 on the European Tour. Could Sunday at Valhalla be third time lucky this season?
The Austrian is level with Rory McIlroy on -12, with the Open champion on the par-five 18th.
Day and McIlroy don't mess about on the 18th tee, both high and mighty and straight...
Not a pleasant shot for Palmer, feet on the edge of a bunker, ball above the feet, and he sprays a hybrid right of the green. In case you were wondering what happened to Jim Furyk, he bogeyed 15 and 16 and is the only man not under par today out of the top 40-odd players. That said, he's still seven under.
Ilonen can only make five at the last but that's a 69 to go with a 67 and a 68 and the Finn is nine under. Day makes par at 17, stays nine under. McIlroy putting uphill, left to right, from about 25 feet. Leaves it a couple of feet left but stays joint leader on -12.
Fowler's longun on 18 comes up a couple of revolutions short but that's a birdie for a round of 67 and 11 under. Fowler is looking to make it four top-five finishes in the majors this season.
Day with 158 yards left at 17 and that's pretty ordinary from where he was. McIlroy is in sand out left but that's a peach of an escape, middle of the green.
Palmer chipping on at 17, leaves it five feet short... leaves his par putt a shade right, drops to -9. Fowler with his second on 18, ball below the feet... terrific effort, he's got a longun for eagle and a share of the lead...
Palmer overcooks his approach at 17, Wiesberger almost holes his chip at 18. He'll tap that in for a round of 65 and the joint lead, with McIlroy, on -12. That's also the joint best of the day with Hunter Mahan. Mickelson almost holed his monster but taps in for birdie for a round of 67 and 10 under.
BBC Sport's golf correspondent at Valhalla
"The standard of the majors this year has been as good as any for a long time. There hasn't been a duff one all year."
Hard to disagree. The supremely talented Bubba Watson clinched asecond Masters title in April, Martin Kaymer notched up his second major with a masterful display at the US Open in June and Rory McIlroy landed a first Open title last month in thrilling fashion.
Mickelson hits a glorious hybrid into the 18th, he's got a monster uphill for eagle. Wiesberger with a poor swing but if he gets up and down from there, that's still a birdie. McIlroy pops in for birdie on 16, grabs the outright lead on 12 under.
Former European Tour golfer on BBC Radio 5 live
Wiesberger gets chocs away down the 18th, Mickelson pushes his drive right into the short rough. Fowler makes par at 17, he stays one off the lead, although that's about to be two. Day has plenty to do to make par after his third...
Palmer leaves his birdie putt left of the hole at 16 but taps in to stay one off the lead. Day has got 255 yards to go at 16 and he's going with an iron. Comes up short, maybe should have gone with the old hybrid. McIlroy is slap-bang in the middle of the fairway, he's only got a nine iron - you have to say that's magnificent, stiffs it to two feet. That for the outright lead...
Palmer into 16, from 190 yards, he's got a 12-footer for birdie. Ilonen with a blind second into 17 and that's not half bad, just a touch long. McIlroy slaps another beauty down the middle at 16, Day is in Robin Hood country... but gets a lucky bounce out...
Mickelson only makes par at 17 to stay nine under but he and Wiesberger have got eagle chances at 18 and should make birdies if they get their drives away.
DeLaet for birdie at 18 and he's missed that by the width of a fag paper, that's a round of 68 for the Canadian for eight under. Lordy, lordy, look at this from Wiesberger - he's stuck his second on 17 to within six inches of the hole and will nick the outright lead on 11 under... SCRATCH THAT! McIlroy joins him on 11 under with a 12-foot birdie putt at 15... Day misses his, stays -10...
Steve Stricker could be playing his way into Tom Watson's Ryder Cup team - currently a US vice-captain, he's birdied 16 to get to seven under par. Jason Day and McIlroy safely on in two at 15, chances for birdies and the outright lead...
Graeme McDowell, Europe's Ryder Cup heroin 2010, says he has no doubts over his place on the team for Gleneagles next month.
"I want to be in the automatic spots if I can. I'll be out there all guns blazing tomorrow and Ryder Cup is of course very important to me," McDowell tells BBC Radio 5 Live.
"I'm not uncomfortable. I'm optimistic about the way I'm playing, I'm optimistic about finishing in the automatic spots and I'm optimistic about a pick. I hope to be there in some shape or form. I've showed the captain I'm playing well, so I'll keep some energy in the tank and hopefully get the call up."
McDowell is currently in the team via the world points list, though Luke Donald and Stephen Gallacher are hunting the Northern Irishman and Jamie Donaldson, currently the final two in the nine automatic places.
Ilonen playing into 16 and it comes up short and rolls away. Stenson up the hill for eagle at the last... drifts right but that's a round of 67 for -9 and a share of the clubhouse lead.
Bernd Wiesberger has not been overawed by playing in the company of Mickelson today, he's just knocked in a birdie on 16 to make it a five-way tie for the lead. McIlroy saves par at 14, stays -10, as does Day. Water down the right on 15 and Day finds sand off the tee. McIlroy going with the big boy and that's a monster...
Canada's Graham DeLaet has been flying under the radar all week but he's just birdied 16 to get to eight under. Mickelson makes that birdie at 16, he's now nine under, one off the lead and hurtling towards the clubhouse like a man on fire.
Mickelson has got things going on and here he is with a crackerjack approach at 16, chance for a third straight birdie. Westwood makes the most of a fine bunker shot at 18, popping in for birdie, a round of 69 and -7 overall. He's not out of this by any means.
Ilonen on 15, 173 to the flag, safe as houses. Day on tee at the 204-yard 14th... all over the pin and 15 fete past. Fowler for birdie at 15, leaves it a touch left, stays -10. McIlroy struggling to hold this together at the moment, he's tugged his tee shot left at 14.
John McEnerney: Turning out to be a cracker of a Major, Top players playing some top golf also making mistakes which is keeping it interesting!The Pete: I'm trying to think of a sportsman and a phrase more associated than Lee Westwood and 'good putt, just missed'. Is there one?
Lee Cattermole, yellow card?