Australian golfer Cam Davis has held his nerve to scrap his way into the second leg of the PGA Tour's lucrative season-ending playoffs for a third straight year.

Davis produced a bogey-free final-round three-under-par 67 to tie for sixth at the FedEx St. Jude Championship in Memphis, Tennessee to leap from 62nd in the season-long points standings to 45th.

Only the top 50 progressed to this week's BMW Championship in Illinois.

In a double bonus, making the penultimate event of the year also guarantees Davis a start in all eight signature events next season, which each offer $US20 million ($A31 million) in prize money.

"I've turned a really kind of up-and-down year into a pretty positive year just out of three really good weeks in a row," the 28-year-old said of his third consecutive top-10 finish.

"The last three Sundays in a row have all been about the same level of stress and the same level of achievement for me.

"I've managed to put really good clean rounds together when the pressure has been on to keep moving forward, and yeah, it's really satisfying to be able to know that I've got a tee time next week.

"So I can start looking forward to that."

Davis collected birdies at the fourth, fifth and 11th holes to finish at 11 under, four shots behind Lucas Glover, who edged out fellow American Patrick Cantlay on the first playoff hole to claim a second win in a row.

"I had a rough sort of estimate of where I felt like I needed to finish based on little things that I had seen throughout the day, but I wanted one more birdie but it looks like I didn't need it," Davis said.

Jason Day is the only other Australian still in the playoffs.

The former world No.1 dropped from 11th to 21st in the standings after sharing 52nd spot on Sunday at two under.

But Day at least found something late with a four-under final round.