Viktor Hovland rode a hot putter to the top of the Arnold Palmer Invitational early in the second round at Bay Hill on Friday.
The world number four from Norway had seven birdies in a six-under par 66 to take the clubhouse lead on nine-under 135.
He was wrapping up his round when first-round leader Rory McIlroy teed off, the Northern Ireland star opening with a bogey at the first hole to drop to six-under for the tournament.
England's Tyrrell Hatton was in the clubhouse on seven-under after a four-under par second round. Former FedEx Cup champion Billy Horschel carded a second-round 71 for a six-under total.
Hovland needed just 23 putts as he built on the momentum of his first round that featured three birdies in his last four holes on Thursday.
"I knew I putted well, but I didn't know it was 23," Hovland said. "It felt like I putted good yesterday. My speed was maybe a little bit off, and I still feel like I can improve on that a little bit even after today.
"I just really saw the lines really well and (was) able to start it online. Sometimes when you see a couple go in early, it's easy to keep that feel going throughout the day."
Hovland rolled in an 18-foot birdie at the 10th hole to open his round, and added an eight-footer at the 12th. After his only bogey of the day at the 13th he launched a run of three straight birdies with a 26-footer at 15.
"I hit a really bad shot on 15 off the tee, and it ended up in the bunker," Hovland said. "I hit a really nice seven-iron jsut pin high left and made that putt, so that was a big hole."
At the par-three 17th, Hovland's five-iron off the tee left him less than 10 feet for birdie.
"That was a nice way to kind of get into 18 and then obviously starting the front nine," said Hovland, who added two more birdies coming in and saved par from just off the green at the 18th.
Going into the weekend, Hovland is hoping to lay the ghost of last year, when after two solid rounds he was 11-over on the last two days.
"I kind of try to forget the weekend here last year," he said.
