The Australian, who had yesterday been three over through 13 holes of his first round at Quail Hollow before rattling home, continued the momentum to charge to outright third this morning.
However, changes to several holes and the installation of bermuda rough and greens had not suited the four-time major victor, who struggled to consecutive rounds of 72 to lie 10 shots off the lead at halfway.
Kevin Kisner was efficient as ever with his wedges and putter in posting a 4-under 67 in the second round.
Ryan Fox, son of World Cup winning All Black, Grant, shot the lowest score of the day, a five under par 66, to close within seven of the lead. Yet Lahiri said, "I hit the ball even better than yesterday (the first round), but again I had a start where I missed a 3-4 footer for par and started with a bogey". He's in contention without having played his best golf yet.
Matsuyama, 25, said the pressure of sharing the overnight lead may have had an impact as he bids to become the first Japanese player to win a major. Matsuyama is looking to win his first major. That should have got me better scores, because if you miss the green it is hard to chip at times. On the back nine, he had three bogeys in a row from third to fifth, before stemming the rot with a par and then closed the day with three straight birdies for a card of one-under 70 and was Tied-15th.
Spieth failed to take advantage of the easier afternoon conditions, making just one birdie in a 73, his hopes of becoming at 24 the youngest player to complete the career grand slam all but gone. The group only five shots behind featured Justin Thomas, Rickie Fowler and Paul Casey.
"I think what was making me exhausted was I wasn't hitting my driver like I wanted to". I told a few guys after golf is gone and done for me, all you have left is people and the relationships you have.
Starting on the 10th hole, Scott's round began with a double-bogey at the 11th and the 37-year-old dropped another two shots before the turn. "I'm sure going to give it a try".
The four-time major victor then made birdies on the par-five seventh and the par-four eighth to all but secure his place for the weekend. If he can find this zone this weekend, where bad tee shots still find the middle of the fairway, and bad irons are still in birdie range, there isn't anyone in the world who can stop him. 14-15). That helped him to a 68, moving to 2 under for the tournament and into a tie for seventh place.