Jason Day in the mix at TPC Sawgrass

Evin Priest
Jason Day is six shots off the lead after his second round at the Players Championship in Florida

Jason Day has surged up the leaderboard during the second round but former US Open winner Webb Simpson is threatening to run away with the Players Championship.

Day, the 2016 winner, fired a bogey-free round of five-under-par 67 and at eight-under he sits six shots back from the lead.

Simpson is soaring at 14-under and has established a four-shot lead as he navigates the back nine at TPC Sawgrass on Friday.

Already in the clubhouse at 10-under are South Africa's Charl Schwartzel (66) and American youngster Patrick Cantlay (68), while Chesson Hadley (69) is solo third a shot back at nine-under.

Taking advantage of calmer morning conditions, Day's second round began with two front nine birdies before he added three more on his inward nine.

The former world No.1's approach play was stellar, hitting 15 of 18 greens in regulations despite only hitting seven of 14 fairways.

"It was nice to be able to get out there and shoot 67, five birdies, no bogeys," Day said after his round.

"I think I started tidying up a few of the areas I had (trouble with) last (week) and I think the swing is coming along.

"I just need to focus on the good progress I made and try and take it into the weekend."

Next best of the Australian contingent is Adam Scott, the 2004 Players champion, who has picked up two birdies in 10 holes to climb to five-under the card.

Scott's countryman Marc Leishman is three shots back having carded a second straight 71, while Geoff Ogilvy ensured he will miss the cut with a 74 dropping him to eight-over.

Rounding out the Australian contingent is Cameron Smith (six-over) and Rod Pampling (seven-over)

Two-time Players champion Tiger Woods is expected to make the projected 36-hole cut of one-under right on the number after he backed up his opening 72 with a 71 on Friday.