Rahm had five birdies on the first nine in a bogey-free roundHero World Challenge second round leaderboard-10 J Rahm (Spa), H Stenson (Swe); -9 D Johnson (USA), P Cantlay (USA); -8 T Finau (USA); -6 G Woodland (USA), A Norwegians (Swe); -5 R Fowler (US) -4 K Bradley (US), J Rose (J), J Thomas (US); -3 X Schauffele (US), B DeChambeau (USA); -2 T Woods (USA), H Matsuyama (Jpn), B Watson (USA), P Reed (USA); -1 J Day (Aus)
Spaniard Jon Rahm shot a nine-under-63 to share half of the lead during the Hero World Challenge in the Bahamas.
The 24-year-old world number eight became a member at 10 under by the Swede Henrik Stenson, who was a 66.
Englishman Justin Rose, looking for a top-three finish to return to the number one in the world, had seven birdies in a 70 and six shots from the start.
Speech host Tiger Woods avoided penalty after a controversial scoop from a bush and ended two under.
Woods was five under for his round when his tee shot at the last finish under a palmetto bush and he tried an escape while he knelt in the sand.
Replays showed the ball remained on the face during the shot, but after lengthy discussions, officials decided against giving a penalty.
"I did not feel like I was breaking rules," said Woods, who ended with a double bogey. "I tried to make an attempt, but the rules committee said they might be a violation, I did not feel like I had hit it twice, but under super slow-mo you could see that I had two contacts made."
The vice president of rules and competitions of the PGA Tour, Mark Russell, said: "We had to watch slow motion video at high speed to determine that the ball probably stayed on the face for too long. how he could have known it. "
Russell explained the rules below and added:" In short, if the player did not know he did [hit it twice] and the only way to know it , by using this type of slow-motion technology, he is exempt from the rules, so there is no penalty. "
From 1 January, players will not be punished for an accidentally double hit.
There is no cut in the elite 18-man field, with 14 of the world's top 20 and nine major winners.
One of those, world number three Dustin Johns on, is only one of the lead after five birdies in six holes on the nine backs in a round of 67.
Woods could barely make a backswing in the palmetto bush