The second-round leader, who was trying to regain some type of form, struggled to a three-over 75 on Saturday. Woods bogeyed his first three holes and fell into a tie for eighth, six shots behind Senden.
Woods knocked it over the green with his approaches at one and two. Those errant irons led to bogeys, then he missed a 10-footer for par at No. 3. He got a stroke back with a seven-foot birdie putt at the fourth, but bogeys at 11 and 12 knocked Woods further down the leaderboard.
A birdie at the par-five 14th couldn't salvage a bad day for Woods.
"I got off to an awful start," Woods said in a televised interview. "The way I hit the golf ball, it was probably a round where I should have shot even-par, maybe a one-under. I made nothing. If I putt normal, it's a one-under-par round with no problem."
Now he'll be chasing Senden, who finished 54 holes at 12-under 204.
Jason Day celebrated his 24th birthday Saturday and shot a four-under 68. He is alone in second place at 11-under 205 at The Lakes Golf Club.
Greg Chalmers managed a five-under 67 in round three and is alone in third at minus-10.
Senden broke into red figures with a short birdie putt at the par-four fifth. He knocked his approach over the flag at six, but spun it back into the hole for an eagle.
The 2006 Australian Open champion birdied the ninth, then hit his second to inches to set up an easy birdie at the 10th. Senden rattled off back-to-back birdies at 13 and 14 and was 10-under par for the championship.
Senden birdied the par-five 11th to get to 11-under, then rolled in a 35-foot birdie putt at the last to get first place on his own.
This is the final week for preparation for The Presidents Cup at Royal Melbourne. American team member Nick Watney shot a four-under 68 and is tied for fourth with Nick O'Hern, who carded a 66 at nine-under 207.
Jarrod Lyle (69) and Ryan Haller (65) are tied for sixth at minus-eight.
Woods was joined in eighth by one of his American Presidents Cup teammates, Bubba Watson, whose even-par 72 on Saturday matched Woods at six-under 210.