Johnson closed with a 70 to finish in second, one shot ahead of Colt Knost. The 2007 U.S. Amateur winner overcame an early triple bogey to shoot a final-round 73 and earn his best PGA Tour finish. Knost finished T-3 at the Mayakoba Golf Classic in February.
Pettersson has now won every other year on the PGA Tour dating back to 2006, when he captured the Memorial Tournament for his second win.
Luke Donald lost the top spot in the Official World Golf Ranking to Rory McIlroy, who did not play this week. Though Donald closed with a final-round 71, he finished T-37 and shy of the top-8 finish required to maintain the No. 1 ranking.