A week after needing a special exemption into next month's US Open, the 50-year-old rolled back the years with a second round of 69 to set a halfway target only matched by former Open champion Louis Oosthuizen.
On a high-quality leaderboard two-time winner Brooks Koepka was ominously poised just a shot off the lead, with Masters champion Hideki Matsuyama another stroke adrift alongside Branden Grace and Christiaan Bezuidenhout.
Tweet of the day
Musician Sam Harrop puts an appropriate soundtrack to footage of an in-sync Rory McIlroy and Brooks Koepka during Thursday's first round.
Quote of the day
"Don't get out of the way guys, let it hit your ankles" – Jordan Spieth warned spectators about his wayward drive on the third, but would have still liked a bit of assistance.
Shot of the day
Round of the day
Phil Mickelson was two over par with eight holes remaining, but played them in five under for a superb 69.
Statistic of the day
Leading statistician Justin Ray puts Mickelson's performance into perspective.
The par-five seventh played to an average of 4.6, with Brooks Koepka among those to make an eagle on the downwind hole.
Despite the tee being brought forward by 16 yards, the 17th played the toughest with an average of 3.68.
After relatively tame winds Saturday morning, expect easterly winds to become breezy and turn southeasterly at 10-14mph Saturday afternoon. Breezy conditions are expected to develop Sunday afternoon, with westerly winds turning southwesterly and becoming sustained at 12-16mph along with gusts to 20mph.
Key tee times
3.30pm BST – Rory McIlroy
7.20pm BST – Christiaan Bezuidenhout, Hideki Matsuyama
7.30pm BST – Books Koepka, Branden Grace
7.40pm BST – Phil Mickelson, Louis Oosthuizen