Four players were tied for the lead shortly after the action started again following a delay of an hour and 18 minutes due to bad weather before Justin Rose, who had been out in front after both the first and second rounds, edged ahead again with a birdie-2 at the 12th on a long day at Augusta National.
However, Matsuyama followed an eagle from close range at the par-5 15th by producing brilliant iron shots to set up back-to-birdies at the 16th and 17th as the 29-year-old suddenly moved into overdrive.
He was in danger of dropping his first shot of the day after over-shooting the green at the last but saved par with a lovely chip down the slope to come home in 30 for a seven-under-par 65.
That matched Rose’s opening effort and moved Matsuyama to 11-under, with Rose, American pair Xander Schauffele and Will Zalatoris and Australian Marc Leishman leading the chase.
Matsuyama has been inside the top 10 entering the final round of major championships eight times in his career - all since 2015 - without managing to get the job done.
His best finish was a tie for second in the 2017 US Open, having also been in the top six in the three other big ones, and now he’s set up his best chance yet to finally make that breakthrough.
“It will be a new experience for me being the leader going into the final round in a major,” he said. “I will prepare well and do my best tomorrow.”
Matsuyama, who only hit five out of 14 fairways during the round, came alive after the weather delay, covering the last eight holes in six-under when play restarted.
“Before the horn blew, I didn’t hit a very good drive but, after the horn blew for the restart, I hit every shot practically how I wanted to,” said the leader.
Asked what he’d done during the delay, he added: “I spent the hour sitting in my car looking at my phone.”
The double WGC winner is bidding to make it a Japanese double in Georgia after Tsubasa Kajitani landed the 2021 Augusta National Women's Amateur in a play-off last Saturday.
“I wasn’t able to watch it as I was playing last week in Texas, but it was fantastic and I hope I can follow in her shoes and again make Japan proud,” he said.
Rose, a two-time runner-up in this event, started birdie-birdie before finding it a real struggle thereafter, but the 2012 US Open champion handed himself a boost by holing a good par putt at the last as he signed for a 72.
“It was a tricky day out there today,” he said afterwards. “There was a period of time after the delay where there was an opportunity to make a score, but the greens slowed up a lot and adjustments needed to be made.
“I had to work hard. After 12 holes, I thought I was in a nice spot, but then Hideki obviously hit the jets and I kind of hit the brakes a little bit and that was the difference.
“Whenever you are four back, you’ve got a chance and only being behind one guy makes it an even better chance. A lot has to do with how Hideki plays tomorrow, but there’s a big chasing pack ready to pounce.”
That also includes Canadian Corey Conners who had a hole-in-one at the sixth as he moved to six-under, one ahead of 2015 winner Jordan Spieth.
American pair Brian Harman and Tony Finau are next on four and three-under respectively, with Scottish No 1 Bob MacIntyre tied for tenth on two-under with Austrian Bernd Wiesberger and Korea’s Si Woo Kim.
World No 2 Justin Thomas ran up an ugly triple-bogey 8 as he slipped to one-under after getting to six-under earlier in the round.
It was another frustrating day in this event for US Open champion Bryson DeChambeau as a 75 left him tied for 38th on two-over.