Friday, 7 September 2018:

JASON DAY of Australia plays a shot from a bunker on the ninth hole during the final round of the Farmers Insurance Open at Torrey Pines South in San Diego, California.

Jason Day admits he needs to divert his attention from the $US67 million FedEx Cup playoffs series and focus on the shot at hand after a lacklustre opening round at the BMW Championship.

The 2015 BMW Championship winner sits five shots off the pace after day one at the penultimate event of US PGA Tour finals, having posted a three-under-par 67.

Tiger Woods and Rory McIlroy equalled the course record of 62 at Philadelphia's Aronimink Golf Club to top the leaderboard at eight under, with Xander Schauffele (63) a shot back in third.

Former world No.1 Day, a perennial contender in the playoffs, sits in a healthy 10th on the overall FedEx Cup standings.

But the Queenslander says he needs to keep it simple with three rounds remaining at the BMW.

"It's very easy to get ahead of yourself in the playoffs and think, 'I haven't got off to a great start so I need to perform now'," Day said.

"Yes, the goal is to get into the top-five, but I can't do that without focusing and giving 100 per cent on each individual shot.

"If I do that the rest will take care of itself."

Cameron Smith seemingly hit a roadblock after consecutive top-three results in the opening two playoffs events, struggling to a one-over 71 in scorching hot conditions which combined 38-degree temperatures with 51 per cent humidity.

"Yeah, it was a little bit tiring," Smith said.

"I can definitely bounce back, though.

"I feel like I played pretty good today just nothing went my way; if I hit a half-decent shot it would end up in a bad spot."

Marc Leishman started his BMW title defence poorly, dropping four shots during a 74 which countryman Adam Scott matched.

AAP