Phil Mickelson played himself right into contention to become the oldest major champion in history after taking the clubhouse lead on day two of the US PGA Championship.

The 50-year-old looked in good shape in his first round on Thursday and he went a step further on Friday, finding himself top of the leaderboard having gone around the Ocean Course at Kiawah Island in 69.

It meant the American was on five under for the tournament, and he was leading by two shots shortly after he had finished for the day.

For much of Friday it looked as though Branden Grace was going to be in charge, the South African sitting pretty at six under for the tournament as he stepped up to the tee on the 17th.

But he finished his round with a double-bogey and a bogey as the breezy conditions took their toll on the two holes regarded as the toughest on the entire course, meaning he walked off after his final hole three under for the tournament.

Mickelson had similar issues on the same two holes earlier in the day after starting on the 10th, though the five-time major winner only dropped two shots across the 17th and 18th – it clearly was not enough of a wobble to really impact his mood.

The 2005 US PGA Championship winner has not had a single top-10 finish on the PGA Tour this season, but he has a great chance to end that here.

Opening up on his brilliant start at Kiawah Island, he said: "Physically I've felt as good as ever, I've been able to perform to play the shots, but I haven't been able to be as present or sharp mentally to visualise the shots I want to play.

"Meditation has been a big part of me being able to play the shots I want. It's gotten more difficult as I've got older to focus. Your mind is like a muscle, you have to exercise.

"That's what I've been doing, some days playing [as many as] 40-45 holes to make sure I can concentrate longer than just 18."

Mickelson carded five birdies after the turn, playing a huge role in putting him into contention to surpass Julius Boros as the oldest ever major winner at 48 in 1968.

Additionally, he is the first man aged 50 or over to be in top-five contention after 36 holes at a major since 2013.

His form here is made all the more remarkable by the fact he needed a special exemption to even qualify for next month's US Open, given his current ranking of 115.

"I'm having a lot of fun," he added. "To play well, to know I'm playing well heading into the weekend, to be in contention, to have a good opportunity, I'm having a blast. I'm excited for the weekend."

Ian Poulter looked to be putting himself into contention as well only to fall apart in the latter stages of his round, carding four bogeys in his final five holes – he was previously six under for the day.

Similarly, overnight leader Corey Conners' dropped down to two under for the tournament thanks to a difficult three-over second round.

Meanwhile, world number one Dustin Johnson will almost certainly not be returning on Saturday as he followed up a shocking first day with comparatively poor two over on Friday, leaving him on six over.

Jordan Spieth faces a nervy wait, he sits at four over following a second-round 75.

Brooks Koepka dismissed concerns over his knee, insisting he does not have to be "100 per cent" after impressing on day one of the US PGA Championship.

Koepka ended the opening round two strokes behind leader Corey Conners and tied for second position following his three-under-par 69 on Thursday.

American star Koepka has been plagued by injuries since winning back-to-back PGA Championships in 2019 and a fourth major title in three years, undergoing knee surgery in March before missing the cut at last month's Masters.

Koepka overcame a slow start after double-bogeying his opening hole in windy conditions as he made history in South Carolina.

The four-time major champion has opened the PGA Championship with a score in the 60s in each of the last six years, the longest such streak at any major in the modern era (since 1934), eclipsing Jack Nicklaus (five – 1972-1976 Masters).

"It's a major. I'm going to show up," Koepka said when asked about his fitness and whether it was the best he has felt since returning from injury. "I'm ready to play. I've been itching to do this since Augusta.

"I mean, I feel so much better now. I don't need to be a hundred percent to be able to play good."

"I love it when it's difficult," said Koepka. "I think that's why I do so well in the majors. I just know mentally I can grind it out. Like when it's windy like this, it's not so much putting, it's more about ball striking, and I felt like I struck it really well today. I feel like that's why I've done really well.

"You've got to understand that sometimes par is a good score. You've got to understand that 30, 35 feet is a great shot sometimes, and you've just got to accept it and move on."

Defending champion Collin Morikawa closed out day one a shot further back at two under.

Morikawa mixed five birdies with three bogeys to end the round three strokes off the pace at Kiawah Island Golf Resort.

He played alongside big-hitting Bryson DeChambeau (72) and praised the reigning U.S. Open champion.  

"I think people need to give him credit, starting today, that he's actually picking up the pace," Morikawa said. "It was amazing how fast he actually played. I'm not going to say fast, but he wasn't slow. You weren't just waiting on him to figure out whatever.

"Kudos to him because it was windy and he had to figure out some stuff for sure. But I enjoy it. He's a character. He's his own person. That's what makes Bryson, Bryson. I think that's why people love him. I enjoy playing with someone like that. It's not going to faze me that he hits it a hundred past me. I know I can still hit it and play golf."

DeChambeau, who heads into the second round tied for 31st, added: "The wind just kicked my butt. It's hot. Just grinding out there, it takes a lot out of you. Working really, really hard to hit every shot the exact way I want to, and then it doesn't happen, and you've got to be comfortable with it and going, okay, how do I get up-and-down.

"It's windy and you're over a four-footer. Wind is blowing really hard, and you think it's going to break. When the wind stops, it's not going to break. It's all just a really difficult thing that you've got to control out there. It's a lot of work."

Corey Conners savoured his "really special round" after defying windy conditions to set the early pace at the US PGA Championship.

Conners earned a two-shot lead on Thursday, the unheralded Canadian golfer upstaging a star-studded field with a five-under-par 67 in South Carolina.

Without a victory since his solitary PGA Tour triumph at the 2019 Texas Open, Conners was almost flawless in gusty conditions, holing six birdies with just one bogey.

Conners' lead marks his third career 18-hole lead/co-lead on the PGA Tour (0-for-two to date) and first at a major. Earlier this season, the 29-year-old was tied for the first-round lead at the Arnold Palmer Invitational and finished third – his best result of the season.

"It was a really special round. I did a lot of things really, really well. Like I said before, it's really nice to see some mid-range birdie putts fall in the hole," Conners said.

"Really gave me confidence and felt like I rolled it really well for the rest of the round. A lot of putts had chances to go in and I made some nice saves, as well."

Prior to Thursday's first round, Conners' best position after any round of a major was equal sixth through 54 holes at this year's Masters at Augusta, where he eventually finished tied for eighth.

Conners bettered that at Kiawah Island Golf Resort, where he tops the leaderboard ahead of four-time major champion Brooks Koepka, Keegan Bradley, Viktor Hovland, Aaron Wise, Sam Horsfield and Cam Davis.

"I have a lot of belief in myself, and I've been playing well for quite a while," said Conners. "I'm excited for opportunity to play against the best players in the world and put my game to the test.

"I have a lot of confidence in my game and I'm excited for the rest of the weekend. Didn't try to force it to happen but definitely saw myself having a good day today and hopefully can keep that up the rest of the weekend."

Corey Conners withstood hammering winds to claim a two-stroke lead following the opening round at the US PGA Championship as Brooks Koepka impressed but Rory McIlroy and Dustin Johnson struggled.

Prior to Thursday's first round in South Carolina, Conners' best position after any round of a major was equal sixth through 54 holes at this year's Masters at Augusta.

Conners bettered that at Kiawah Island Golf Resort, where the Canadian defied the wind to set the early pace with a five-under-par 67.

Without a victory since his solitary PGA Tour triumph at the 2019 Texas Open, Conners was almost flawless in gusty conditions, holing six birdies with just one bogey.

Conners' lead marks his third career 18-hole lead/co-lead on the PGA Tour (0-for-two to date) and first at a major. Earlier this season, the 29-year-old was tied for the first-round lead at the Arnold Palmer Invitational and finished third – his best result of the season.

Koepka ended day one in a share of second position alongside Keegan Bradley, Viktor Hovland, Aaron Wise, Sam Horsfield and Cam Davis.

Koepka has been plagued by injuries since winning back-to-back PGA Championships in 2019 and a fourth major title in three years – the American star underwent knee surgery in March before missing the cut at last month's Masters.

But Koepka impressed on Thursday, overcoming a slow start to shoot a three-under-par 69.

Koepka double-bogeyed his opening hole on the back nine, however, the four-time major champion only dropped one shot after that as he tallied six birdies.

He has opened the PGA Championship with a score in the 60s in each of the last six years, the longest such streak at any major in the modern era (since 1934), eclipsing Jack Nicklaus (five – 1972-1976 Masters).

Defending champion Collin Morikawa is a stroke further back alongside the likes of five-time major winner Phil Mickelson.

Big-hitting American and reigning U.S. Open champion Bryson DeChambeau signed for an even-par 72 at the close of the first round, level with Jon Rahm and Justin Rose, while Masters holder Hideki Matsuyama, former world number one Jordan Spieth – eyeing a career Grand Slam – and Xander Schauffele shot 73s.

Jason Day and Patrick Reed were also further down the leaderboard as two-time PGA Championship winner McIlroy and world number one Johnson were powerless in the wind.

McIlroy – seeking a first major trophy since 2014 – recorded a three-over-par 75, which included six bogeys and just three birdies.

Justin Thomas also went three over for the day, while Johnson finished with two double-bogeys and a bogey in a forgettable four-over-par 76 display.

Rory McIlroy struggled on his return to Kiawah Island with a three-over-par 75 in the opening round at the US PGA Championship as playing partner Brooks Koepka impressed.

McIlroy won by eight shots the last time the PGA Championship was staged at Ocean Course in South Carolina in 2012 and was installed as the favourite of many after ending a winless streak of almost two years at the Wells Fargo Championship two weeks ago.

However, the four-time major champion – seeking a first major title since 2014 – landed his very first shot into the water on a windswept morning before recovering somewhat with back-to-back birdies on Thursday.

McIlroy – a two-time PGA Championship winner – was level par at the turn after dropping another shot on the par-five 16th, but he managed just one more birdie compared to five bogeys as he closed for 75, eight shots behind Corey Conners.

Koepka played down expectations heading into the tournament due to a knee injury and he started slowly with a double-bogey on his first hole, though the two-time PGA Championship winner recovered well with two birdies in the next three holes.

After turning in 36, Koepka picked up three shots in four holes on the front nine to complete an impressive turnaround that saw him earn a share of the lead before Conners soared to the summit as he aims to add to his successes in this event in 2018 and 2019.

"I felt like an idiot," he told Sky Sports Golf when reflecting on his cagey start. "It was probably a poor club choice off 10. I thought three-wood would have carried, but it didn't. I also didn't find the face, it barely hit the face!

"The first rule is, if you're in trouble, get the hell out. I couldn't reach the green and it was a bad lie, so I didn't know where I was going. I just tried to hit a sand-wedge up by the green instead of just chopping it out.

"So it was a mental mistake there, and I deserved every bit of that double-bogey. But it kind of helped me refocus. I can't play with any mistakes, maybe one a day, and that was my one, and I got it out of the way on the first hole."

Koepka is joined on three-under par by former champion Keegan Bradley, Viktor Hovland. Aaron Wise and Sam Horsfield.

Bradley's opening round included four birdies and just one dropped shot, coming on the par-four 13th, while Hovland bounced back from an opening bogey with four birdies.

Collin Morikawa is one shot further back after bogeying his final hole, the defending champion joined on a first-round 70 by Martin Laird, who was also let down by a couple of dropped shots on his final two holes.

Justin Thomas finds himself way down the standings, meanwhile, after carding a three over that included a double-bogey on the 18th, while US Open champion Bryson DeChambeau had a mixed first day as he posted a level-par 72.

World number one Dustin is among the late starters, along with Jordan Spieth, Tommy Fleetwood and Justin Rose.

Energised by the return of spectators, Rory McIlroy is confident he can end his major drought at this week's US PGA Championship.

McIlroy arrives in South Carolina buoyed by his drought-snapping victory at the Wells Fargo Championship earlier this month.

Not since November 2019 had McIlroy reigned supreme on the PGA or European Tour but the former world number one ended his wait at Quail Hollow.

McIlroy has not won a major since 2014, however the 2012 and 2014 PGA Championship winner feels good heading into Thursday's opening round.

"I'm happy with where my game is, so I guess if I go out and play my game and do what I know that I can do, then I can see myself shooting good scores on this golf course," four-time major champion McIlroy told reporters.

"So that's sort of where I'm at. Whether that means I win or not, that's partly up to me, but that's partly on how the other 155 guys in the field play, as well.

"I've just got to go out there, play my game, and if I play my game somewhat close to the best of my ability, I'm sure I'll have a good chance."

Fans returned for the Wells Fargo Championship amid the coronavirus pandemic as McIlroy thrived en route to glory and there will be fans at Kiawah Island this week.

"It's funny, ever since I was 16 years old I've had thousands of people watch me play golf pretty much every time I teed it up. Even going back to amateur golf and. So then not having that, playing in that environment for 14, 15 years and then sort of going the complete opposite, it's just different," he said.

"I said at the time it was like playing practice rounds. It's easy to lose concentration. Everyone is used to a certain environment, whether you work or whatever you do, and it's a bit. I watched the Champions League semi-finals a couple weeks ago and those guys play in that for the first time in their careers and they're playing in an empty stadium. That just must be terrible. That's not at all how you dream of being in a squad like that and playing in a massive game.

"You want to play in front of people and you want to feel that atmosphere. It's unfortunate that in these times a lot of people don't have that experience, but I am glad that we're getting back to some sort of normalcy, and when you hit good shots and hole putts there is claps and rewards and encouragement.

"I feel like that's all a part of tournament golf and competitive sports at the highest level, and just happy that I'm starting to come back."

Another former world number one, Jordan Spieth, is eyeing a milestone at the PGA Championship.

Spieth, who ended his fourth-year title drought in Texas last week, can become the sixth player in history to complete the career Grand Slam and the first to do so by winning a PGA Championship.

The three-time major winner, though, played down his career Grand Slam quest.

"I think as we get into the weekend, if I'm able to work my way into contention, I think it's something that'll obviously be asked and come up, and it's something that I certainly want," Spieth said.

"You go to a major, and for me at this point, I want to win the Masters as badly as I ever have this year. Didn't happen.

"I want to win this one as badly as I ever have. Once you move on to the U.S. Open, the same. Majors, that's what we're trying to peak for those.

"I feel like I'll have a lot of chances at this tournament, and if I just focus on trying to take advantage of this golf course, play it the best I can and kind of stay in the same form tree to green I've been in, all I can ask for is a chance."

Brooks Koepka said he can play through the pain in his bid for a third US PGA Championship but a full recovery from a knee injury remains months away.

Koepka has been plagued by injuries since winning back-to-back PGA Championships in 2019 and a fourth major title in three years.

The American star underwent knee surgery in March, having won the Phoenix Open, and he has missed the cut in his past two events, including last month's Masters.

As Koepka gears up for Thursday's opening round at Kiawah Island Golf Resort in South Carolina, the 31-year-old acknowledged his knee is still problematic but he is ready to play.

"I feel like I can hit every shot. It's not like Augusta where I'm trying to figure out what's the best line to walk instead of figuring out. Now I can actually hit golf shots and understand what's going on," Koepka, who has been paired alongside Justin Thomas and Rory McIlroy told reporters on Tuesday.

"For a while it was just I neglected putting just to see if I could hit shots, because if I can't hit shots I can't play. No point in that. No, I got everything under control and know what I'm doing. Last week was a good test just to see where I'm at for two days.

"I thought if I got four, it would be nice, but two days of rest didn't hurt me."

Asked for a timeline for him to be fully healthy, Koepka replied: "We're talking probably another six months."

"If I beat that, I'm doing something good," he continued. "I mean, I can play. You're never 100 per cent, that's the thing. For two straight years it's been left knee, right knee, herniated a disc in my neck, played in Tampa or wherever we were, played through that. I dealt with that all the way through Palm Springs.

"I can deal with the pain. That's not an issue. It's just a matter of being able to hit shots that I want to hit and do things I want to do, and I'm starting to be able to do that. Even though I'm not 100 per cent, I can still hit the shots."

Koepka added: "Every day has been a long day. Starting from just the training to the rehab, everything seems to take an hour, hour and a half longer, more attention to detail of what I'm doing off the golf course, make sure I'm doing -- I seem to get hurt in a bunch of freaky instances.

"It's just one of those things where you've just got to move past it and take it one day at a time."