Brendon Todd said his putting was "lights out" as he took a share of the lead at the US PGA Championship on Thursday.

The American carded a five-under 65 at TPC Harding Park in San Francisco to share the lead with Jason Day after the opening round.

Todd, who finished tied for 15th at the WGC-FedEx St. Jude Invitational last week, said he putted at his best during the first round.

"It was lights out. I couldn't have putted any better, there's no doubt, and I did this last week," he said.

"The first round, I had a lights-out day putting, and, again, I've always watched guys shoot those low opening rounds and it's really just the guys who are confident.

"Week in, week out, their games are rolling. It's nice to be able to do that."

Todd made a nine-foot putt for par at the final hole to ensure he led overnight with Day.

The 35-year-old said it was a key moment to ensure he went into the second round with some momentum.

"I think it really helps me going into [Friday]. It allows me to spend the next 12 hours before my second round feeling really good, like I've got momentum still," Todd said.

"I would say it's really just, for this moment, it means a lot but after that, it's just going to be another score at the end of the week."