In only his second appearance in the event and 12 years after the first one, the 48-year-old Hampshire man sits alongside American Russell Henley on five-under-par after two circuits in the 121st edition at Torrey Pines, just north of San Diego.
The pair hold a one-shot lead over 2010 Open champion Louis Oosthuizen and big-hitting American Matthew Wolff, with two-time Masters champion Bubba Watson and world No 3 Jon Rahm lurking on three-under.
Defending champion Bryson DeChambeau sits on level-par alongside two-time winner Brooks Koepka, Collin Morikawa and Justin Thomas, with a group on one-over including 2011 winner Rory McIlroy and Lee Westwood.
Oozing confidence after that breakthrough success in the Betfred British Masters at The Belfry, Bland had opened the season’s third major with a one-under-par 70, setting up that solid start with a holed bunker shot.
But could he back it up as one of the early starts on day two? ‘Yes’ was the answer as Bland, who played in his first major back in 1998, produced another polished performance in a rare appearance alongside the game’s big guns.
For the second day running, he opened with a birdie and, helped by three more, was out in two-under. He then added gains at the second, fourth and sixth on his inward journey before a plugged lie in a bunker led to a bogey at the par-3 eighth.
Though he was unable to birdie the par-5 ninth, it was brilliant stuff from the world No 115 - the same position fellow oldie Mickelson occupied when he became the game’s oldest major winner at 50 in last month’s US PGA Championship at Kiawah Island.
“To lead a major is always pretty special,” said Bland after signing for a 67. “I tied the lead at The Open [at Royal Birkdale] in 2017 for a hole, so it is nice to have it a bit longer than that.”
Before a closing three-putt hiccup, Henley, the co-low amateur in the 2010 US Open, was poised to become only the 10th player since 2011 to have two or fewer bogeys through the first 36 holes. Four of those nine had gone on to win the championship.
The 32-year-old Georgian, a three-time PGA Tour winner, has hit 26 of 36 greens. Considering he shot a 79 in his only previous round on the South Course in the 2014 Farmers Insurance Open, he has thus far found a formula for success.
“It feels very fair out there,” said Henley, whose last victory came four years ago in the Shell Houston Open. “It feels like you just have to put the ball on the correct side of the hole. It's just been really difficult.”
Playing a couple of games behind Bland, MacIntyre once again showed his fighting qualities on the biggest stages to almost certainly make it six cuts in six starts in majors.
Having opened with a level-par 71, MacIntyre set out on the second day just outside the top 20 before quickly finding his back against the wall as he dropped three shots in his opening five holes before spilling another one at the 17th - his eighth.
Time and time again, though, in the formative stage of his professional career MacIntyre has shown that he’s made of stern stuff and this was yet another occasion.
The 24-year-old got down in two from long range to pick up his first birdie of the day at the par-5 18th before rolling in a five-footer for another gain at the second.
Brad Faxon and Claude Harmon Jnr are the latest Americans to express admiration for MacIntyre and it’s easy to see why as he went on to cover his last 10 holes in two-under with little room for error.
The left-hander signed for a 73 for a two-over total and will be looking to kick on over the weekend as he bids to pick up both world ranking and Ryder Cup points.
With each performance in these events, having tied for sixth in the 2019 Open then finishing 12th on his Masters debut in April, MacIntyre is showing European captain that he wouldn’t let him down at Whistling Straits in September.
Mickelson, who is bidding to complete the career grand slam on the back of becoming the game’s oldest major winner at 50 in last month’s US PGA Championship at Kiawah Island, was delighted with his second-day fightback after struggling in an opening 75.
“I played really well today,” said the newly-turned 51-year-old San Diego man. “I struck the ball really well, and it made it a lot easier. I was able to play aggressively.
“I didn't probably take advantage of all of the opportunities that I had, but I played a good solid round of golf. I'm playing well enough to make a run on the weekend.”
Martin Laird, the other Scot in the field, missed the cut on his return to the event after a four-year absence, carding five bogey as he came home in 40 for a second-round 76 and an eight-over total.
Others to make early exits included Justin Rose, Henrik Stenson, Tyrrell Hatton, Will Zalatoris, Web Simpson and Dundee-based Frenchman Victor Perez.
Norwegian Ryder Cup contender Viktor Hovland withdrew during the second round because of an eye injury.
The 2018 US Amateur champion had completed 10 holes after carding a three-over 74 in Thursday’s first round.