Smith faces a tough week to stay in the PGA Tour's US$78.5 million FedExCup Playoffs but improved his chances with a hot first round at the Northern Trust – the finals opener in New Jersey.

The 25-year-old Queenslander mixed five birdies with a bogey during a four-under-par 67 at Liberty National to sit five shots behind first-round leader Troy Merritt.

Merritt equalled the course record with a stunning 62.

At nine under, he leads former World No.1 Dustin Johnson (63) by one shot while major winners Rory McIlroy and Webb Simpson (65) are also in the hunt.

At 79th on the FedExCup standings, Smith needs a hot result at the Northern Trust to climb into the top 70 who advance to next week's BMW Championship, the second of three finals events.

"It's a kick in the butt, knowing I have to play well the next two weeks," Smith told AAP at Liberty National, which sits just across the Hudson River from New York City.

RIGHT: Smith opened with four-under 67 at Liberty National. PHOTO: Kevin C. Cox/Getty Images.

After the BMW, the Playoffs are cut to 30 players who qualify for the season-ending Tour Championship.

Making the Tour Championship guarantees contestants starts in all four majors next year without relying on world rankings.

There is a lot at stake for Smith, but the Brisbane native says being able to frequent one of his favourite US cities is a welcomed distraction.

"I love New York City; we went into Manhattan for dinner last night and really like the vibe," Smith told AAP.

"I always seem to play my best golf when I'm relaxed off the course and I feel I can do that here."

Smith is tied at four under with fellow Australian Matt Jones (67), while Adam Scott (68) is a shot behind.

But Australians Jason Day (72) and Marc Leishman (73) struggled on day one, while Aaron Baddeley withdrew citing a back injury and is now out of the Playoffs

Meanwhile, Tiger Woods, who has finished second in both times the Northern Trust was last held at Liberty National, struggled during a sloppy 75 which dropped him to four over.

- Evin Priest, Australian Associated Press