JASON Day is losing his grip on the US PGA Tour's $US10 million ($A14.22 million) FedEx Cup bonus and World Number One ranking as Henrik Stenson took command at the halfway mark of the Tour Championship in Atlanta.
Day, who came to East Lake Golf Club in Atlanta on top of the world and the season-long points race following four wins in his last six starts, struggled to a one-over-71 in the second round on Friday, leaving him at even-par and nine shots behind leader Stenson.
It was just the second over-par effort from Day in his last 30 rounds.
Stenson, who won the FedEx Cup in 2013 and who is guaranteed the bonus again if he goes on to win the tournament, shot 68 to move to nine-under, three clear of his nearest rival.
Former Number One Jordan Spieth, who will also claim the bonus with a win and who can retake top spot in the world with victory and help from Day, made his move with a sublime 66 in tough wet conditions.
He moved to second place at six-under while England's Paul Casey (70) is third a shot further back.
British Open winner Zach Johnson (70) sits fourth while Australian Steven Bowditch continues to match it with the big guns after a 69 left him tied with Rory McIlroy (71) in fifth at three-under.
If Spieth wins and Day is outside the top five he would return to Number One. McIlroy can also retake top spot if he wins and Day is outside the top 15.
Currently tied ninth, Day is prepared to get back in the hunt on moving day.
"It is very difficult but there is a score to be had out there, especially on the front side where you can get it going," Day said.
"If I can shoot four or five under tomorrow and Stenson holds his position, then anything can happen Sunday.
"These holes coming in are pretty tough and certain numbers can happen on those holes if you are not quite sharp so the plan will be to try to put some pressure on the guys up top."
Bowditch rebounded from a double bogey at the ninth to birdie two of his last five holes, becoming one of just eight of the 28 players in the field to be under par.
The two-time US Tour winner sits nicely poised in an impressive Tour Championship debut thus far.
"It's been going well and just the one blunder today. To finish under par was pretty good considering that was a very tough set up and we had the rain, the 24th seeded Bowditch said.
"I just need a run of five to eight holes where you sort of get the putter hot and a few go in and three or four under in a little stretch can have you right in the mix.
"I'm looking forward to the next two rounds and having a crack."
TOUR CHAMPIONSHIP SECOND ROUND LEADERBOARD
|T5||STEVEN BOWDITCH (AUS)||-3|
|T9||JASON DAY (AUS)||E|
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