Smith bracing for brutal Bethpage at PGA May 14, 2019 by AAP / Evin Priest

NEW YORK CITY, AAP - Cameron Smith is bracing himself for a fierce examination at this week's US PGA Championship on New York's Bethpage Black golf course.

The 25-year-old Queenslander has never played the famously-difficult layout on Long Island and was unable to tee up in practice on Monday as heavy rain washed out the course in the afternoon.

Smith was restricted to short-game practice only, while fellow Australian stars Jason Day, Marc Leishman and Adam Scott were not at the venue.

World No.29 Smith was not in the field when the 7400-yard Bethpage Black hosted the 2012 and 2016 Barclays tournament during the US PGA Tour's playoffs series.

"Basically, all I've heard is how hard it is, and how long it plays, and it's going to play long this week," Smith told AAP on Monday.

While the rain is set to disappear for Tuesday and Wednesday practice rounds, temperatures are forecast to be 18 degrees or lower throughout the week.

It's a dramatic weather change for the major championship, which is being held in May for the first time.

Previously the PGA occupied a mid-summer August date and was known for its sweltering heat and humidity.

Smith is among eight Australians in the field, including 2015 PGA Championship winner Day, Scott and Leishman.

The quartet are joined by rising European Tour star Lucas Herbert and the Japan Tour's Brendan Jones, as well as PGA Professionals Championship qualifiers Stuart Deane and Craig Hocknull.

Smith is coming off two consecutive missed cuts on the US Tour and hasn't finished in the top 10 since the WGC-Mexico in February.

But the Florida-based Smith says a two-week rest has him recharged and feeling ready for a return to form.

"I've had a couple weeks off which is nice and refreshing and good for the melon (mind)," Smith said.

The entire top 100 golfers inthe world rankings were set to contest the PGA Championship before world No.5 and 2017 winner Justin Thomas withdrew on Monday due to a wrist injury.