DUBLIN (AFP) - Tiger Woods shrugged off early round back pain and a horror start to birdie three of his closing five holes in a level par effort on day one of the Memorial Tournament on Thursday (May 31).

Woods had struggled to be four-over par through just seven holes ahead of recording a level par 72 in ideal conditions at the Jack Nicklaus-hosted event.

It left world number 83 Woods trailing seven strokes behind the leading clubhouse duo of Chile's Joaquin Niemann and Mexican Abraham Ancer who recorded seven-under-par 65s.

Woods, who started on the 10th, struggled from the outset in missing his opening three fairways and taking a second hole bogey before sending his drive at his sixth way right into a hazard from where he was forced to take a penalty drop on route to a double-bogey seven.

He then dropped to four-over-par in bogeying the next before arresting his slide with a birdie at his eighth hole.

Woods made the turn in three-over and then played his inward half in three-under par thanks to three birdies in succession from his 15th hole and ending with two pars including a six-footer for par on his last.

"I wasn't rotating very well today, back was tight, and just it is what it is some days," Woods said.

"I made a few tweaks in my swing, my setup, and lo and behold I was able to make some good swings on the back nine, well, my back nine, and turned the whole thing around so at least I've now got a fighting chance." Woods is a five-time Memorial winner and is teeing-up in the event for a first time since 2015. However in nine rounds here since he won a fifth Memorial title in 2012, he has failed to crack 70.

"It is what it is," Woods said. "Just got to make the adjustments. I'm able to make them now.

"At the beginning of the year, I wasn't able to make them, because I didn't really know what to do yet. But now you see me making these adjustments on the fly."