Mickelson, along with Keegan Bradley, lost in a playoff Sunday to Bill Haas at the PGA Tour's Northern Trust Open in California one week after winning the AT&T Pebble Beach National Pro-Am.
That boosts Mickelson from No. 11 to ninth in the rankings. He switches places with Charl Schwartzel. Mickelson started the year ranked 14th.
Haas moves from 22nd to No. 12 and Bradley is 19th, up seven spots from a week ago.
European Tour winner Jbe Kruger jumps 50 spots to No. 109 after his win at the Avantha Masters in India. It was his first European Tour title.
Luke Donald remains No. 1 in the world with a rankings points average of 9.257 but Rory McIlroy moves back past Lee Westwood and into the No. 2 place. McIlroy's average is 7.806, just higher than Westwood's 7.797. Neither played last week, however.
Martin Kaymer is fourth at 5.960 and Steve Stricker (5.677) is No. 5. Webb Simpson stays at No. 6 with a 5.170 average, not far ahead of No. 7 Jason Day (5.109) and eighth-ranked Adam Scott at 5.098 Mickelson comes in at 5.053 and Dustin Johnson (5.025) is 10th.