Jordan Spieth underlined his desire to keep hold of the prized Claret Jug after moving into a share of the lead at Carnoustie on Saturday.
The 2017 champion golfer of the year started the third round three strokes back, but eagled the first after a booming drive to signal his intent.
Having carded a 67 on Friday, he capitalised on even more favourable conditions on the east coast of Scotland to sign for a fine 65, putting him level with Xander Schauffele and one ahead of Kevin Kisner.
The closing holes that had done so much damage in his opening two rounds proved far more manageable for the three-time major winner, who leads a chasing pack that includes the likes of Rory McIlroy and Tiger Woods.
Not since Padraig Harrington in 2008 has a player successfully defended their Open title. McIlroy, who won this tournament in 2014, improved his overnight score by three to sit on seven under through 15, while Woods' best major round in seven years - a stunning 66 - saw him close only one worse off.
But, 2015 winner Zach Johnson, who shared the lead with Kisner at the start of play, endured a miserable start to his back nine and dropped back to five under.
Kisner held firm to remain within a shot of the lead through 13, with Justin Rose boasting the round of the day - his 64 coming after he needed a last-hold birdie just to make the cut.
- Jehan Daruvala to make professional debut next year in Formula E with Maserati MSG Racing
- Asian Games 2023 LIVE, September 27 Updates: Anant wins silver in men’s skeet; Esha bags silver in 25m pistol; Nikhat Zareen in action soon; India 5th with 22 medals
- IND vs AUS live score 3rd ODI: Kuldeep, Bumrah strike twice as Australia loses six wickets
- SA20 hopes to become biggest T20 league outside IPL, says commissioner Graeme Smith
- Table Tennis LIVE Score, Asian Games 2023: Sathiyan, Manika qualify for R-16; Sreeja, Harmeet in action