WGC-Mexico Championship 2017: Saturday Leaderboard Scores and Highlights

After 54 holes at the WGC-Mexico Championship, Justin Thomas took sole possession of the lead at 12-under par thanks to a 66 on Saturday.

Thomas overtook Dustin Johnson late in the third round thanks to back-to-back birdies on No. 15 and 16. Johnson helped him along the way with a bogey on No. 16 that dropped his score to 11-under par.

The big story from Saturday was Jordan Spieth reminding the world he is not to be overlooked. He rose 31 spots on the leaderboard after a brilliant 63 brought his score to seven-under par, five shots back of the lead.

Here's the full leaderboard after 54 holes at the WGC-Mexico Championship:

This looked like a week in which Spieth would just be happy to make it through 72 holes without having a bad round, then ramp up his preparations for the Masters starting on April 6.

If there's one thing sports have taught us, especially over the last 12 months starting with the Cleveland Cavaliers' comeback from a 3-1 deficit in the NBA Finals, it's never to count out a great athlete.

Per Golf.com, instead of retreating into his shell, Spieth decided to set a new course record:

Starting his third round on the back nine, Spieth immediately went to work with birdies on No. 11 and 12. He finished with six birdies, one eagle and no bogeys to climb within shouting distance of the lead heading into the final round.

Following his round, Spieth was appropriately pleased with his performance and confident heading into the final round, via PGA Tour:

To help illustrate how Spieth was able to post the lowest single-round score at this tournament so far, Justin Ray of the Golf Channel provided these numbers:

Kyle Porter of CBS Sports humorously added another layer to Spieth's round that will also impact what happens on Sunday:

One week after capturing the No. 1 spot in the official world rankings, Johnson can lose it if he finishes outside the top three and Spieth wins on Sunday.

The good news for Johnson is he's still got a good-sized lead over Spieth to maintain his spot atop the world rankings.

While Spieth is going to command a lot of headlines, Thomas did provide this highlight on No. 13 to make sure he would be in the conversation heading into Sunday, via PGA Tour:

After starting the tournament with a 69 on Thursday, Thomas offered an interesting quote about a certain aspect of his game, via Rex Hoggard of the Golf Channel:

Whatever Thomas has done over the past 48 hours seems to be working out well for him as he goes after his third win of 2017, following the SBS Tournament of Champions and Sony Open in January.

Adding to the star power looking for a victory on Sunday, Phil Mickelson and Rory McIlroy are tied for third place at 10-under par.

This round was something of a disappointment for McIlroy, who entered the day with a two-shot lead. He struggled on the front nine with an even-par 35 thanks to three birdies and three bogeys before settling down with a bogey-free back nine that included one birdie on No. 11.

Mickelson continues to show excellent day-to-day consistency with scores of 67-68-68 to be in the mix for his first PGA Tour victory since the 2013 U.S. Open.

It's also nice to see that Mickelson is still able to pull off those shots no one else on the tour would even bother to attempt, like this one on No. 10, via PGA Tour:

As for how Mickelson was able to card his second consecutive 68, the PGA Tour provided the stats:

It's not always the prettiest stat sheet for Mickelson, but his ability to save himself from a disaster is unmatched. He will need to take a couple more chances on Sunday if he wants to take home the title.

This is the PGA Tour's dream scenario heading into Sunday. Spieth, Johnson, Mickelson and McIlroy are all right in the thick of things.

Thomas is still the one to beat after firing back-to-back rounds of 66. The drama will be off the charts with just 18 holes left from Mexico City.