Daniel Berger surges five clear at Bay Hill as he eyes first PGA Tour win in five years

The 32-year-old American moved to 13 under par at the halfway stage after carding a four-under 68 at the demanding Bay Hill course in Florida.

"The green speeds are up there. The pin positions are tough," he said.

"It's just one of those courses. It's treacherous," Berger added.

Akshay Bhatia sits second after producing the round of the day, a 66 that included seven birdies, highlighted by a 36-foot chip-in at the eighth.

"I'm just going to keep plodding along... (Berger) could run away with it and I could be playing for second or it could be a little bit of a challenge," he said.

"There's a lot of guys within six shots of the lead, which is not much around Bay Hill."

Sweden's Ludvig Aberg and recent Pebble Beach champion Collin Morikawa are a shot further back on seven under, alongside Sahith Theegala, who climbed the leaderboard with a bogey-free 67.

Rory McIlroy, preparing to defend his Masters title next month, was pleased with a 68 after an erratic even-par opening round. McIlroy made five birdies and one bogey, the latter coming at the par-four eighth where he found the water but limited the damage with a 10-foot putt.

"I really felt like that kept any momentum that I had for the round going. I played the last 10 holes really, really well," he said.

World number one Scottie Scheffler endured a frustrating day and finished at three under, tied for 15th after closing with a bogey on the 18th.