Choi - now heads the betting.

By David John

Sky Bet's Odds Compare All Prices

Bettingzone's 33/1 pre-tournament tip KJ Choi has a one-shot lead after the first round of the Northern Trust Open and is now 9/2 clear favourite at Paddy Power and bet365 for victory.

The Korean carded six under 65 at Riviera to lead from Kevin Na - the latter is a 25/1 chance at Stan James.

Phil Mickelson is the current 11/2 second favourite (Blue Square) after he begun with a three under 68 while Ireland's Padraig Harrington is also right in contention after a 69 - he can be backed at a general 20/1.

Chad Campbell is on offer at the same price with totesport thanks to an opening 67.