TOUR Championship 2015: Leaderboard Scores and Highlights from Thursday

Henrik Stenson registered runner-up finishes in the first two FedEx Cup events this season but may be on his way to a second PGA Tour playoff title in three years after a brilliant start to the TOUR Championship on Thursday.

Stenson put the golf world on 59 watch at East Lake Golf Club in Atlanta when he roared out to a six-under 29 on his first nine holes. The strapping Swede put on a stripe show and got as low as eight under through 12 before ultimately settling for a round of seven-under 63 to grab a two-stroke lead over Paul Casey.

Something about the venue has brought out the best in Stenson, per Golf Channel's Justin Ray:   

New world No. 1 Jason Day had won four of his previous six starts entering the FedEx Cup finale and appeared to be making a bid for golf's magical 59 to start his round. Day birdied his opening three holes and missed a good chance at the par-four fourth to add another.

An ugly, unusual turn transpired at the fifth when Day flared his tee shot out of bounds to the right, leading to a triple-bogey seven. He bounced back with a birdie at No. 7 but missed from close range at the par-five ninth to turn in one under. Day couldn't get anything going on the back and played level par in for 69.

Casey capped his day off well ahead of Day in score and actual time, since he's 22nd in the FedEx Cup standings. The Englishman may have had the quote of the day after a round in which he, according to Golf Channel's telecast, was 15-of-15 putting from inside 10 feet, per PGATour.com's Amanda Balionis:

But Stenson has a realistic shot at knocking Day off his recent perch atop the game thanks to Day's turbulent opening round. Stenson is currently fourth in the FedEx Cup but would take the $10 million bonus and hardware if the results held as they are now.

Check out the eagle Stenson sank in the heart of the cup just before the turn, courtesy of the PGA Tour's official Twitter feed:

Another name near the top of the leaderboard is Rory McIlroy, who enjoyed a rather lengthy stay atop the world rankings until Day and Jordan Spieth had breakout years. McIlroy's season was slowed by an ankle injury, but he appears to be saving something special for Atlanta.

A round of four-under 66 saw McIlroy build on a tie for fourth at last week's BMW Championship and continue to show improvement on the greens. Putting has been the weak point of McIlroy's game since his return at the PGA Championship, but he's making enough strides to suggest he'll be in contention come Sunday.

Following an inauspicious start at one over through seven holes, McIlroy heated up with three consecutive birdies on Nos. 7 through 9. Prior to a gutsy two-putt at the par-three closing hole, he struck a brilliant iron approach to the 17th:

Frequent frustration followed Spieth as he was paired alongside Day in what's been an underwhelming postseason for the young stud who won the season's first two majors. Spieth still managed to score well on 68 but has some work to do to catch up to Stenson.

There's still a chance Stenson can walk away with the FedEx Cup without winning at East Lake. Based on his recent close calls and his winless season to date, though, Stenson figures to be keen to take the trophy.

John Bazemore/Associated Press

The problem is McIlroy may be finding form at the perfect time to deny Stenson yet again, though the 26-year-old needs a bit more help at 11th in the FedEx Cup standings to claim the ultimate prize.

It wouldn't be a surprise to see McIlroy steal back the spotlight after Day and Spieth have been at the forefront of golf coverage in recent months. Shane Bacon of Fox Sports highlighted just how impressive Day and Spieth have been to earn top billing:

The man who took the Claret Jug from the idle McIlroy at The Open Championship, Zach Johnson, is tied with McIlroy at four under and can't be counted out either.

The TOUR Championship is certainly filled with intriguing subplots after only 18 holes of action. These next three rounds are bound to present a memorable conclusion to the playoffs as Stenson seeks to stave off a surging McIlroy and numerous other big names still in the hunt with plenty of golf to play.

Note: Stats courtesy of PGATour.com unless otherwise indicated.