The Swede had four bogeys and a birdie over the first nine holes at Torrey Pines. The big slump came on holes 11-15 - resulting in five straight bogeys for Åberg.
Two closing birdies salvaged the 26-year-old's round somewhat. But Åberg has never before recorded nine bogeys in a single round on the US Tour, according to Expressen.
The Eslöv native finished six strokes over par for the day, placing him in 143rd place - tied for last place. Åberg had to cancel last weekend's season premiere due to illness.
Jesper Svensson is the best Swede at -2. Henrik Norlander is on par and Alex Norén is on +3. Englishman Justin Rose leads at -10.
Corrected version: In a previous version, an inaccuracy was stated about who was the best Swede.
