Hossler, who played the par-72 Spyglass Hill, had five birdies in a five-under 67 that put him on 12-under as well.
Elwewhere Graeme McDowell - back at the scene of his greatest triumph, when he won the 2010 US Open - opened with a one-under-par 71 at Pebble Beach.
"The biggest thing for Rory is the desire part - how much does he really want it - because he has the tools to be Tiger-esque", the Australian (30) said.
He sounds as though he can't wait to get going, especially after his start in the Middle East portion of the European Tour schedule when he tied for third in Abu Dhabi and lost a lead on the back nine in finishing second to Li Haotong in Dubai. When you have a bunch of screws in there and a couple of plates, you've got to be careful about how much reverberation you have running up that collarbone, so I gave it a lot of time to heal.
"I don't know if it's quite as good as it was during that stretch". Lowry went around Monterey Peninsula while McIlroy played Spyglass Hill, meaning the Offaly man actually came in one shot less, even though they are tied on the same score. This year it's going to be a little different because the weather's so good and the course is playing firmer, I think it will move quicker than last year when we were walking with umbrellas.
He said: "I've been hitting the ball beautifully".
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The pro-am event sees the professionals and their partners also playing a round at Monterey Peninsula before the final day's action takes place at the famous Pebble Beach public links. Rory McIlroy, Jordan Spieth, Dustin Johnson, Phil Mickelson and Jon Rahm will all play and are among the heavy favorites to take home this year's tournament.
After nearly driving the green, the Northern Irishman used his putter from the fringe and stroked the ball to within six feet of the cup, from where he took four putts and probably ended his hopes in the tournament in a matter of seconds.
McIlroy was four-under through 15 holes before suffering a bogey on the 16th, when his wayward drive finished in a waste area.
Though there were far too many continuing good signs in McIlroy's game to dwell on any negative.
He was one-under for the tournament, with work to do on Saturday to make the 54-hole cut.