NORTON, Massachusetts (Reuters) - Tiger Woods says he has shaken off his back problems and is confident his recent weekend struggles are not part of a new trend as he sets his sights on this week's Deutsche Bank Championship.

Woods entered the PGA Tour's lucrative four-event playoffs at the top of the FedExCup standings but faded in last week's Barclays tournament, finishing in a tie for 38th after being inside the top 10 at the midway point.

His slide was partly attributed to a tweaked back after sleeping on a soft hotel bed, although he managed the pain successfully during his second round at Bethpage Black.

"The back is good," world number three Woods told reporters on Thursday while preparing for Friday's opening round at the TPC Boston. "It was nice to have the treatment there on the weekend and then have Monday off.

"It's nice this tournament starts a little bit later, so I've got an extra day to kind of get some more treatment at home," he said of the unusual Friday start. "Yesterday, it felt great. I hit it really well, and had no issues at all."

Woods slipped to third in the FedExCup standings after The Barclays and, though he is guaranteed a spot in the season-ending Tour Championship in Atlanta, his recent poor form over the weekend has prompted some to question his 'killer' instinct.

"You can't really look at it as real bad, going on this year," said Woods, who has fallen backwards in the last three majors after being in contention going into the weekend.

"At the time, most of the year, I was leading the money list, I was number one in FedExCup points and I won three times, so it's not like it's been that bad."

Woods, a 14-times major winner, has won three PGA Tour events this season, more than anyone else.

"It's just a couple rounds here and there or it's an up‑and‑down here and there or it's making one putt," said the 36-year-old American who won the Deutsche Bank Championship in 2006, one year before the FedExCup was launched.

"I played all right (in practice) today. I worked on a couple things ... I'm not that far off."

Ninety-eight players are in the field at the TPC Boston and the top 70 will advance to next week's BMW Championship in Carmel, Indiana.

Only 30 players will then qualify for the Sep. 20-23 Tour Championship finale in Atlanta where the overall points winner pockets a $10 million bonus.