PEBBLE BEACH, California, Feb 12 (Reuters) - Defending champion Dustin Johnson held onto a share of the lead after the second round of the Pebble Beach National Pro-Am on Friday.

Overnight leader Johnson shot a two-under 68 at the Monterey Peninsula Country Club’s Shore Course to finish 10-under (132) with a clutch of players after two rounds.

The American was joined by compatriots Bryce Molder, Paul Goydos and J.B. Holmes, as well as Germany’s Alex Cejka and Matt Jones of Australia.

Former world number one David Duval is a stroke behind the leaders after shooting a 68 at Pebble Beach Golf Links.

Johnson took the outright lead after a birdie on the 13th, but dropped a stroke on the 17th to fall back into the pack, his only blemish in an otherwise flawless round.

Jones, the only one of the leaders to play his round at Pebble Beach, notched eight birdies in his five-under 67, but rued a run of three consecutive bogeys.

Goydos, who played the Spyglass Hill course, considered the toughest of the tournament’s three courses, posted a seven-under 65 for the best round among the leaders, his first sub-70 round at the course in 14 appearances at the event.

The American has been named an assistant Ryder Cup captain by Corey Pavin, and will hope for a strong finish to achieve his goal of breaking into the team.