The Irishman??is in a group four shots off the lead after firing five birdies and a bogey during a solid first round, but admits he could???ve finished higher up the leaderboard.
Speaking to Sky Sports Golf???s Tim Carter, Harrington said: ???It was one of those days where if I???d finished five-under I would be very happy and I???m disappointed with four-under, but surely one shot can???t make a difference over 72 holes?
???I had three good chances on the last three holes and it looked like I???d holed all three of them. None of them went in, but that can happen.???
Harrington won his first tournament in over four years at December???s Indonesian Open, but has made a disappointing start to the new season with missed cuts at the Phoenix Open and the Farmers Insurance Open.
???I???d be better off in contention,??? the 43-year-old added ???When you???re in contention you???ve got just one job ??? to get it done ??? so I would find it easier if I was under that sort of pressure.
???I struggle a little bit at times with my focus and it???s the easy shots that I sometimes struggle to execute.???
After missing out on the Farmers Insurance Open title last week in a play-off defeat to Jason Day, JB Holmes bounced back by carding an eight-under opening round 64 to move joint top of the leaderboard.
Holmes fired seven birdies and an eagle to end day one level with Justin Hicks and admits he???s keen to learn from his Torrey Pines disappointment.
???Maybe things will go a little bit different this week,??? the world No 49 said. ???I’ve just got to keep reminding myself it was a great week for me and I did everything I could do and just carry that on to this week.”