Last season, the competition was played at Torrey Pines because of severe fires in Pacific Palisades. Åberg won then.
This year, the players were back at The Riviera Country Club, where Olympic golf will be decided in 2028.
The Swede finished the day at five under par, a total of -9, far from the top spots. Åberg finished tied for 20th place.
Åberg has had a tough start to the season due to stomach problems for which he has sought treatment, but said at a press conference before the Genesis Invitational that he was starting to feel better.
Alex Norén was the best Swede, tied for 12th at -11.
The winner was Jacob Bridgeman. Bridgeman shot one over par in the final round but finished at -18 overall, one stroke ahead of compatriot Kurt Kitayama and Northern Irishman Rory McIlroy.
