Former world number one Jordan Spieth earned a share of the Phoenix Open lead following a stunning third-round performance on Saturday.

Not since the 2017 Open Championship has Spieth claimed a title – the three-time major winner falling to 92nd in the world rankings as a result.

Spieth also missed six cuts in 20 events last year, while also failing to reach the weekend at the Farmers Insurance Open to begin his 2021 campaign.

But Spieth is on track to end his drought at TPC Scottsdale in Arizona, where the American star is level with countryman Xander Schauffele (65) atop the leaderboard heading into Sunday's final round.

Spieth carded a 10-under-par 61 to catapult himself up the standings and to 18 under through 54 holes.

With 10 birdies and no bogeys, Spieth tied his career-low score – he has gone on to win nine tournaments when leading/co-leading after three rounds on the last 16 occasions.

"What I'm looking forward to is just staying the course, trusting it,'' said Spieth, who has his first 54-hole lead/co-lead on the PGA Tour since the 2018 Open. "I have no expectations on the results tomorrow. I really don't.''

"I built some freedom now seeing these results the first few days here to where I feel really good about the path I'm on,'' Spieth added. "I feel good about what the long term ahead looks like for me. And sometimes that's been in question. To myself.''

Scottie Scheffler (66) and Lee Kyoung-hoon (66) are three strokes off the pace, a shot ahead of Louis Oosthuizen (63) and Justin Thomas (64) at 14 under.

Four-time major champion Brooks Koepka posted a third-round 66 after birdieing five of his last six holes to be tied for seventh – five strokes behind Spieth and Schauffele.

Northern Irish star Rory McIlroy dropped down the leaderboard after carding a one-under-par 70 in round three.

Without a win since the 2019 WGC-HSBC Champions, four-time major winner McIlroy is six under overall and tied for 36th position.