FedEx Cup leader Dustin Johnson and US PGA Championship winner Brooks Koepka are one shot off the pace after the opening round of The Northern Trust.

Jamie Lovemark, Kevin Tway, Sean O'Hair and Vaughn Taylor all carded five-under-par 66s to set the early pace at the opening FedEx Cup play-off event in New Jersey on Thursday.

The top 125 from the regular-season FedEx Cup standings qualified for this week's opener, with only the top 100 advancing after The Northern Trust.

World number one and reigning Northern Trust champion Johnson (2,717) tops the play-off standings with three PGA Tour wins this season, ahead of Justin Thomas (2,634), Koepka (2,012), Justin Rose (1,991) and Bubba Watson (1,879).

Bidding to go back-to-back at the tournament, having survived a sudden-death play-off last year, Johnson was almost flawless on day one at Ridgewood Country Club.

Johnson – who almost nailed a hole-in-one on the par-three sixth – had seven birdies, with his only blemishing coming via a triple-bogey on the par-five 17th.

The American star is in a logjam for fifth spot alongside 12 others, including three-time major winner and countryman Koepka.

Koepka posted an eagle, four birdies and two bogeys for a 67 to be within a shot of the leading quartet, along with Tommy Fleetwood, Hideki Matsuyama and European Ryder Cup hopefuls Paul Casey and Rafa Cabrera-Bello.

Phil Mickelson led a group at three under after recently joining Twitter and partaking in some trash talk with Tiger Woods, whom he will play against in a $9million pay-per-view event on Thanksgiving weekend in Las Vegas.

Reigning FedEx Cup champion Thomas carded a first-round 69 to be three strokes adrift heading into day two, while Masters champion Patrick Reed also went two under.

Tiger Woods played early on Thursday, and the 14-time major winner struggled to get anything going.

Woods shot an even-par 71 with two birdies and two bogeys to be joined by Watson, Webb Simpson and Jason Day in a share for 60th spot, a shot worse off than Jordan Spieth.

The day's most shocking round came from Jon Rahm, who fired a four-over 75 following three birdies and seven bogeys.