2020 Tour Championship leaderboard, takeaways: Rory McIlroy goes low, puts pressure on leaders after Round 1

Dustin Johnson and Jon Rahm are on top through 18 holes at East Lake

This is the second year of the staggered start in Round 1 of the Tour Championship, and it's still going to take some getting used to. Dustin Johnson and Jon Rahm co-lead after the first round at 13 under, but they didn't shoot 57s to earn that score. Johnson started at 10 under and shot a 67, while Rahm started at 8 under and shot a 65. 

The top two moved forward in Round 1, which is the opposite of what happened last year when Rory McIlroy jumped the top three on the leaderboard after a big first round. McIlroy played well again in Round 1 this year, but he has a lot of work to do over the next three days in order to get in contention for the weekend.

Let's look at how Round 1 played out at East Lake Golf Club and what to expect going into the rest of the 2020 Tour Championship.

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T1. Jon Rahm, Dustin Johnson (-13): D.J. hit it slightly better than Rahm, but Rahm figured out a way to score and played his last 15 holes in 5 under. It would be fitting if these two battled this weekend at this tournament after their war at the end at Olympia Fields last weekend. Also, if this duo leads a foursome -- that also includes Justin Thomas and McIlroy --  into duking it out all weekend on this course for $15 million, whoa buddy, that would be a pretty sweet ending to a weird year.

3. Justin Thomas (-11): J.T. finished first in the field from tee to green but 22nd (in a field of 30) with his putter. That's been the issue for him of late, but broadly speaking, he's a great putter. I trust that he'll figure it out at some point, and if it's this weekend, he'll win.

4. Rory McIlroy (-9) : Everybody saw it coming from a mile away. How good is a freed-up Rory after weeks of having his mind on his soon-to-be-born daughter? Apparently, he's 64 in Round 1 at East Lake good. McIlroy birdied his last three holes and finished second to J.T. in strokes gained tee to green. He's going to be problematic given where he's at mentally and his history on this course (two wins in the last four years).

"You know, it just shows you golf is such a mental game, and if you come in with low expectations, that's always how I've played well," said McIlroy. "Whether I don't feel like my game is in a good place or I'm not the favorite coming into a tournament, all that stuff, I feel like that's when I usually play my best and I can play with a bit of freedom, and that's what I did today."

5. Abraham Ancer (-7): Awesome day for Ancer to cap what has been a great season. He eagled the last hole to tie McIlroy with a 64, which stood as the round of the day. Ancer hit the ball tremendously over the first 18 holes, and he sounds undeterred by the fact that he started nine down to D.J.

"I just picture myself like if this was a five-day event and I shot 1-under yesterday," said Ancer. "I just have to make some ground. I didn't think it was that weird. I just look at the leaderboard if I need to see where I'm at, and actually, it's quite nice seeing yourself move up with a good round, which on a golf course like this you can do that. It's not a course that you're going to be able to shoot 10 under or 8 under every day, which good solid rounds can really, really make some moves."

T6. Xander Schauffele, Brendon Todd, Sungjae Im (-6): Death, taxes and Schauffele playing well at East Lake. His 1.7 strokes gained on Friday was actually about half of what he averages per round on this course throughout his career (which has been short thus far). If somebody comes from outside the top four to take this thing down, it's probably going to be him. 

CBS Sports was with you the entire way updating this story with the latest scores, updates and highlights below. Check out the scores at the top of this story, a more detailed leaderboard and our complete viewer's guide.

[Sep 4, 2020 at 6:19 pm ET · Kyle Boone]

Jon Rahm is in for par on No. 18 to post a 5-under par 65 in his opening round.

[Sep 4, 2020 at 6:19 pm ET · Kyle Boone]

DJ is in the clubhouse with a 3-under par 67. Strong back nine after making the turn at even-par.

[Sep 4, 2020 at 5:29 pm ET · Kyle Boone]

Holy smokes! Rahm drains a deep putt, and DJ follows with one nearly as deep. Yowza that was sick. Just like last week at the BMW.

[Sep 4, 2020 at 5:29 pm ET · Kyle Porter]

Rory opens with a 64 to get to 9 under. Whoooo boy.

[Sep 4, 2020 at 5:28 pm ET · Kyle Boone]

Jon Rahm is just casually draining 20-plus footers now. That's a thing. He's now 12 under and tied with DJ. His fourth birdie on the back.

[Sep 4, 2020 at 5:21 pm ET · Kyle Boone]

Have a back nine, Rory. Perfectly reads his birdie putt on No. 18 and sinks it to get his fifth (!) birdie on the back. He's in with a six-under par 64.

[Sep 4, 2020 at 5:19 pm ET · Kyle Boone]

Par for Jon Rahm on No. 13 to stay at 11 under and one stroke back of Dustin Johnson.

[Sep 4, 2020 at 5:10 pm ET · Kyle Porter]

Rory is -5 and on the last hole. I saw this coming, and I still didn't pick him!