Tiger Woods struggles in Memorial but Russell Knox in touch

Russell Knox on day one at Muirfield Village
Knox began from the 10th hole and dropped only one shot in his round
Memorial Tournament first round leaderboard
-8 B Van Pelt (US), H Matsuyama (Jpn); -6 J Dufner (US), R Knox (Sco); -5 K Duke (US), R Moore (US), B Todd (US), H English (US), K Kisner (US), D Lingmerth (Swe), K Reifers (US). Selected others -4 J Rose (Eng), J Spieth (US); level P Mickelson (US), R Fowler (US); +1 T Woods (US); +3 B Neil (Sco) (am) ; +4 T Fleetwood (Eng); +5 E Els (SA).

Scotsman Russell Knox was two off the lead after a 66 on day one of the Memorial Tournament in Ohio, but former world number one Tiger Woods shot a 73.

World number 77 Knox, yet to win on the PGA Tour, made seven birdies and dropped his only shot on his last hole.

Woods, now ranked 172, was four over after nine in his first event for a month, but rallied with three birdies.

American Bo Van Pelt had six birdies in his first nine and leads on eight under with Japan's Hideki Matsuyama.

Inverness-born Knox, 29, is in his fourth full season on the PGA Tour and lost a four-way play-off at last year's Honda Classic.

This season he has recorded two third-place finishes and tied for 17th at the Players Championship last month.

Meanwhile Woods, five times a winner of the Jack Nicklaus-hosted tournament at Muirfield Village, began his round from the 10th with a dropped shot after hooking his drive.

The 14-time major champion also bogeyed the next when his approach to the par five found the stream guarding the green.

He drove out of bounds on the right to double-bogey the 18th yet also produced some impressive play too, a magnificent tee shot to three feet setting up a birdie at the par-three 16th which was one of five birdies in his eventful round.

"Physically, I feel good. Mentally I feel beat up," said Woods, who is playing his fifth tournament of 2015 and has a best finish of joint 17th.

Justin Rose, 34, the 2013 US Open champion and world number six, birdied four of his opening seven holes in a four-under 68, which was matched by Masters champion Jordan Spieth.