Tyrrell Hatton kept his return from wrist surgery right on course on Friday, firing a three-under par 69 to share the halfway lead in the Arnold Palmer Invitational with South Korea's Kang Sung.
England's Hatton, playing just his second tournament since right wrist surgery in November, notched his sixth straight round in the 60s and was tied with Kang on seven-under par 137.
Kang, who relished the chilly winds whipping across the Bay Hill course in Orlando, Florida, fired a four-under par 68.
The leading duo were one stroke in front of New Zealand's Danny Lee, whose four-under 67 was the round of the day.
World No 1 Rory McIlroy settled for a one-over 73 and headed a trio of players on 139 along with South Korean Im Sung-jae (69) and Harris English (70).
Hatton said his return tournament, the WGC Mexico Championship, was an ideal comeback event since it guaranteed him four rounds.
"That was interesting to see how my wrist kind of reacted to a full week's tournament golf, and it was absolutely fine," said Hatton, who tied for sixth at Chapultepec.
"No pain out on the golf course, which is important. And I've been able to practice how I want to practice before coming here, and my swing's generally been in an all right place."
Hatton fired five birdies in his three-under round, hitting seven of 14 fairways and 13 of 18 greens in regulation.
"I hit it in some interesting spots," he said. "It's not easy with how strong the wind is."
Hatton, who teed off on 10, was two-under through his first nine after three birdies and a bogey, but said he "lost" his swing coming in.
"I just didn't have a clue where it was going," admitted Hatton, "I was struggling with hitting it quite far left.
"I'm just happy to get in the clubhouse with kind of no damage done," added Hatton, who bounced back from a bogey at the third with a birdie from off the green at the fourth and a 13-foot birdie at the eighth, his penultimate hole.
Kang had six birdies and two bogeys in his four-under effort.
"I drove it great and then putted really nicely," said the South Korean, who is seeking a second PGA Tour title to go with his victory at the 2019 Byron Nelson.
McIlroy, who was one off the first-round lead of Matt Every, was atop the leaderboard by the time he teed off thanks to the erratic American's second-round 83.
"It was a grind," McIlroy said of a round that included three bogeys and a double bogey as well as four birdies. "I made it more of a grind than I needed to."
McIlroy balanced an early bogey with a four-foot birdie at the par-five sixth.
But after a three-putt bogey at the seventh he put up a double bogey six at the eighth - where it took him four shots to reach the green.
"Conditions were tricky," McIlroy said. "The greens are getting firm, wind was out of a different direction today so that made things a bit interesting, too.
"All in all it would have been nice to get back to even par after the double on eight.
"It was nice to birdie 17," added McIlroy, who rolled in a 20-footer to gain a stroke at his penultimate hole. "I'm still right there in the golf tournament."
Overnight leader Every certainly couldn't say the same, and he was joined on the wrong side of the cutline by several familiar names including Justin Rose, Phil Mickelson, Adam Scott and Tommy Fleetwood.
England's Fleetwood saw his streak of 33 straight cuts made, the longest active streak on the PGA Tour, come to an end.
Leading second-round scores on Friday in the PGA Arnold Palmer Invitational at Bay Hill in Orlando, Florida (USA unless noted, par-72):
137 - Tyrrell Hatton (ENG) 68-69, Kang Sung (KOR) 69-68
138 - Danny Lee (NZL) 71-67
139 - Harris English 69-70, Im Sung-jae (KOR) 70-69, Rory McIlroy (NIR) 66-73
140 - Marc Leishman (AUS) 71-69, Patrick Reed 70-70, Christiaan Bezuidenhout (RSA) 68-72, Sam Burns 68-72, Brendon Todd 68-72, Tom Hoge 70-70
141 - Scottie Scheffler 67-74, Rickie Fowler 71-70, Scott Harrington 71-70, Collin Morikawa 70-71
142 - Hideki Matsuyama (JPN) 69-73, Graeme McDowell (NIR) 68-74, Stewart Cink 72-70, Kevin Na 70-72, Danny Willett (ENG) 71-71, Jimmy Walker 73-69, Matt Wallace (ENG) 69-73
143 - Keith Mitchell 68-75, Dylan Frittelli (RSA) 71-72, Patrick Rodgers 73-70, Matt Jones (AUS) 75-68, Charley Hoffman 70-73, Adam Long 69-74, Troy Merritt 71-72, Bud Cauley 71-72