After 18 holes of play at the 2019 Tour Championship, the leader after zero holes (Justin Thomas at 10 under) no longer holds the top slot by himself. That might be confusing, and I'll explain more in a minute. But first, let's take a deep dive into how Round 1 at East Lake unfolded. 

First place -- Xander Schauffele, Brooks Koepka, Justin Thomas (-10): With the predetermined leaderboard based on how players stood in the FedEx Cup standings coming into Thursday, all three of these guys had very different rounds. Thomas, who started at 10 under, had to birdie the last to get back to 10 under with an even-par 70. The difference between BMW Championship J.T. and Tour Championship J.T.? He gained all the strokes on his approach shots last week, and he lost three to the field in Round 1 this week. That left him 29th in a field of 30. 

Schauffele shot a round-of-the-day 64 to rise from 4 under to 10 under and tied with Thomas and Koepka going into Round 2. He had an 8-footer at the last for a 63 and the outright lead that he narrowly missed. Coincidentally, he defeated Thomas here in 2017 when Thomas took the FedEx Cup.

Last place -- Lucas Glover (+3): He actually didn't shoot the worst round on Thursday -- that was Webb Simpson with a 74 -- but Glover shot a 40 on the back and is now 13 back of the lead even though he was just 3 over on the day.

Other contenders -- Rory McIlroy (-9), Patrick Cantlay (-8): Cantlay was my pick this week, and I'm sticking with him. But we've been here before with McIlroy. He won this tournament in 2016 before he burned the Ryder Cup to the ground in Minnesota, and it feels a little bit inevitable (?) that he and Koepka are going to duke it out on Sunday for $20 million combined. 

Who had a great day? Schauffele shot the best score by two strokes, but my sleeper pick, Hideki Matsuyama, shot a 66 and is in prime position to make a move on Friday and Saturday. He was 50-1 coming into the week and is now just 16-1. Hope you took him while you could!

Who had a lousy day? I did not see Webb Simpson's 74 coming. He made just one birdie and lost seven (!) strokes from tee to green in Round 1. He'll rebound, but he's probably too far in the hole to make a real run at the trophy on Sunday.

Stat of the day: It's on my main man, Sungjae Im.

Quote of the day: This from Matt Kuchar destroyed me. Totally out of his world here!

On the new format: It was fine. Xander co-leads, and if this was just a regular tournament he would solo lead. Everyone who would have been in the top five in a regular event (Schauffele, McIlroy, Matt Kuchar, Matsuyama and Paul Casey) is in the top eight on this board. So it's different, but it's not that different. The person hurt the most is probably Im, who was 3 under on the day and would be T6, but because he was just 1 under coming in is now T13.

What to watch on Day 2: Can Thomas rebound? He was so good last week that it was stunning to see him play so (relatively) poorly on Thursday. I highly doubt we get two straight rounds of even-par or worse play out of him. It's a loaded top of the board, though, with McIlroy and Koepka bucking their heads as the weekend approaches in the last event of the season.

CBS Sports was with you the entire way updating this story with the latest scores, analysis and highlights from Round 1 of the 2019 Tour Championship. If you are unable to view the live updates below, please click here.

Thanks for stopping by.