Jason Day believes Tiger Woods looks "impressive" and "ready" to begin his official US PGA Tour comeback after playing a practice round with him ahead of the Farmers Insurance Open.
On Tuesday, 14-time major champion Woods and Australian world No.14 Day beat the bumper crowds anticipated for Woods' first full-field event in 11 months by playing an early morning, nine-hole practice round at Torrey Pines golf course near San Diego.
Former world No.1 Woods endured a near 10-month injury lay-off last year to undergo spinal fusion surgery before making a respectable return at the Hero World Challenge in December, an unofficial 18-man event.
Woods will now make his 2018 debut at Torrey Pines, where he has won eight times, including the 2008 US Open - his last major championship victory.
Woods looked sharp for most of the nine-hole session with fellow former world No.1 Day and American Bryson DeChambeau, mixing some flashes of ball-striking brilliance and deft short-game touch with a few errant tee shots.
What impressed Day most about the 42-year-old's new-look swing was the lack of pain despite Woods' fourth surgery on his back.
After teeing off the 10th hole on Torrey Pines' South course, Woods easily reached the 614-yard par 5 in two shots and outdrove his younger playing partners several times.
"He looks impressive; it was good to see," said Day.
"This time he definitely looks ready; I think his swing is really nice, he's hitting the driver a long way and he looks like he's got some speed, which is great.
"But tournament play is different to (practice rounds)."
However, 30-year-old Day said expectations had to be tempered about the 79-time PGA Tour winner's return.
Last year, Woods' ill-fated injury comeback last year saw him miss the 36-hole cut for the first time at Torrey Pines before withdrawing after 18 holes of the Dubai Desert Classic, citing back spasms.
"The other times he came back I don't think he was ready probably came back too soon," said Day, a close friend of Woods.
"He has hardly played in two years, so I think the biggest thing is to not get too far ahead or think he's going to come back and win straight way.
"He may win straight away, but you never know."
Day is also making his first start for 2018 after last playing at the Australian Open in Sydney in November, where he led going into the final round only to fade to a fifth-placed finish.
The Queenslander has spent the past two weeks practising in the Californian desert, looking to break a winless drought that stretches back to May 2016.
"The game is coming along, I've just got to keep at it. It's the first event of the year, so I've just got to knock the rust off during these last few (practice) days, get into the tournament and try execute good shots," said Day, who won the 2015 event at Torrey Pines.