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Phil Mickelson always seems to be fighting a multi-pronged war. Over the course of his career he has -- for various, overlapping periods of time -- battled an errant driver, an inability to close out his nation's biggest event, unwise decisions engendered by immense hubris and even, briefly, the Securities and Exchange Commission. This week's fight, as Lefty (-7) holds the 54-hole lead at the 2021 PGA Championship by one over Brooks Koepka, is as emotionally taxing as any he's ever taken on in a single week.

Mickelson shot a 70 on one of the best major championship Saturdays in recent memory. His round looked like a graph of a penny stock Mickelson has surely invested unholy sums into. He went out in 32 as histrionics settled in over the Ocean Course at Kiawah Island. It started to feel like a Rory McIlroy redux when Lefty birdied No. 10 to get to 10 under with the par-5 11th in front of him. He made par there, though, which seemed to briefly quell the coronation that was beginning to unfurl.

A bogey at No. 12 was a small step back, but everything was fine until everything was not fine on the 13th. Mickelson, who has driven it quite well this week, jerked a drive into the water on that par 4. After determining it did not cross land (which an overhead video replay confirmed to be accurate), he hit his third off the tee and made double bogey to drop to 7 under. Five straight pars to close out his round -- a few of them incredible, a few others horrific -- gave him a 2-under 70 and the solo lead going into Sunday.

Mickelson's reward for all of that? A pairing with four-time major winner and resident major championship collector Brooks Koepka, who is in the top five after 54 holes for the fourth straight year at this golf tournament. After spending two decades jousting the best player of all time in his prime, Lefty will not be intimidated by Koepka's song and dance like lesser players would.

But Koepka's bravado is only half the schtick. The other half is a tee-to-green game that ranks second in the field this week (behind Mickelson) and shots on Sunday like the one he hit from 282 yards into the 16th hole with a major championship on the line.

This final pairing is a rarity. It's been 40 years since two players with 4+ majors were the top two on the leaderboard going into the final round of a major championship. Koepka (four majors) is trying to join Phil Mickelson and Seve Ballesteros with five; he would be the third-youngest in the modern era to accomplish that feat. Mickelson (five) is trying to join Lee Trevino and Sir Nick Faldo (who will be on the call on Sunday) with six. Lefty would be just the 14th golfer in history with 6+ major championships.

Koepka is one side of Mickelson's Sunday war. Another is how he limped home behind his Sunday playing partner in Round 3. Mickelson had played beautifully for two-and-a-half rounds. The other half of the equation with Mickelson has always been the irrational, supreme confidence (and at times, arrogance) that flows out of his great play. There's a dent in that now, even though he closed out his 70 with gusto.

There are more fronts where battles wage, too. As Eamon Lynch wonderfully pointed out in this Shotgun Start podcast on Friday evening, Kiawah Island is a place that wears you down emotionally. Good shots turn bad, and men who are given plaques and jackets based on cold, hard numbers generally do not deal well with the illogic of a golf course that is not set up to bend reality in their favor.

Lefty has been open about how difficult it's been for him to stay locked in to the show. Though that has not fully slipped quite yet, like the cold Atlantic Ocean water that beats against its shores and erodes the soil underfoot, Kiawah itself erodes the sturdy ground confident golfers seem to stand on. She is unrelenting.

The final battle that Phil Mickelson will enter into on Sunday is an historic one. He has avoided the conversation for most of the week, but he turns 51 next month, and a win here would mean he would become the oldest major winner by nearly three years. In a lot of ways, that actually makes sense. One of Mickelson's superpowers has always been his ability to stay healthy and prolong one of the great careers of all time.

But Mickelson is not stupid. While self-confidence is the clothing he wears, and while he will certainly hope this is not his last run at a sixth major championship, he has to know deep down in that place where the greatest and most talented men reconcile their gifts with their mortality, that the shadows are much longer than they used to be. The sun is much lower than it has ever been. It is touching the horizon and fighting the night, but Mickelson knows what we all know, the sun never wins that battle.

So when he ambles to the first tee on Sunday to shake the hand of the man wearing a goatee that looks like a lost bet, adjusts a snakeskin belt adorned with his logo and asks for a tee and a ball from his brother and caddie, Tim, I bet he pauses for an extra beat.

Not for more than that, though, for men like Mickelson are never long on reminiscing. But I bet Lefty takes a second or maybe two and thinks about how he's been doing this -- contending at big-boy tournaments all over the planet -- for as long as his grown-man playing partner has been alive and how that will not always be the case.

Then they'll hit their shots, and Mickelson will make a walk he's made 10,000 times. It would be incredible for him to ward off the Koepka front and the emotional front and the historic front and beat back the Ocean Course with his driver and that 2-wood. And boy, coming to the 17th and 18th with a lead would make up for a lot of missed time with spectators over the past year.

All I hope for is Lefty turning back from west to east on the 14th hole of Kiawah with a shot at the Wanamaker Trophy. I hope he has a real shot with five holes to go and that he gets to roll home with Koepka in a day that's half as fun as that all-timer on Saturday.

As Mickelson plays No. 14 and then No. 15, maybe he'll think about catching the man talking about him in the booth looming over the stretch of land four holes in front of him. Or maybe he'll think about how he conceivably could have been on that 1991 Ryder Cup team that made this course famous and was the very reason it was built. Or maybe he'll think about how, with a chance to dance -- likely for the last time, in front of a world he helped construct -- he'll have the sun at his back with real history in front of him.

It will feel good, too, to fight that battle pointing toward the east as the course demands you do, because if you don't have to look at the sun set in front of you, you can maybe for a minute think that it simply never will.

Rick Gehman and Mark Immelman break down and react to Saturday's third round action at the PGA Championship. Follow & listen to The First Cut on Apple Podcasts and Spotify.