Bryson DeChambeau and Matt Wallace enjoyed strong starts to the Rocket Mortgage Classic on a day of very low scoring at the Detroit Golf Club.
DeChambeau and Wallace were among seven players to open with six-under 66s which left them just one shot off the lead jointly-held by Doc Redman, Kevin Kisner and Scott Stallings.
In-form Tyrrell Hatton fired a confident 68 along with RBC Heritage champion Webb Simpson, the highest-ranked player in the field this week, while Rickie Fowler's response to back-to-back missed cuts was an encouraging 67.
Redman produced the scoring streak of the day on the back-nine, when he surged to the top of the leaderboard with seven birdies over the last eight holes, and it could have been eight in a row had he not been a touch heavy-handed with a 10-footy putt at the par-five 14th.
He soon had company in the clubhouse lead when Stallings birdied three of the last four to match Redman's 65, and Kisner made it a three-way tie at the top after handing in a clean, seven-birdie card.
Wallace hit the headlines last week when he had to play on his own in round two after Denny McCarthy tested positive for Covid-19 and Bud Cauley also withdrew as a precaution, and the Englishman went on to miss the cut by a distance.
But he got back on track with an excellent eight-birdie opener in Detroit, which he capped with a 40-foot putt for a bonus two at the par-three ninth to join the logjam at six under which soon had DeChambeau added to it.
The bulked-up DeChambeau flirted with the 200mph ball speed barrier on occasions with his driver, but he was inconsistent with his irons and made a number of mistakes which led to bogeys, three of them on the front nine taking the shine of his four birdies.
But after he picked up shots at 10 and 13, he reduced the 550-yard 14th to a driver (376 yards) and a nine-iron to the front of the green, and his disappointment at coming up short was soon forgotten when his 35-foot eagle putt dropped in the centre of the cup.
DeChambeau also birdied 16 and 17 before another short-iron misjudgement at the last cost him a fourth bogey of the day on a hole which Fowler had double-bogeyed a few hours earlier.
However, that proved to be the only Blemish on Fowler's scorecard as he signed for seven birdies and a 67, while Hatton plotted his way neatly around the traditional layout and carded four birdies and no bogeys.
Luke Donald was also four under until he bogeyed his last hole and had to settle for a 69, one of 67 sub-70 scores on the first day, while Jason Day is in a large group at two under which also includes veterans Vijay Singh and Steve Stricker.