(CNN) -- Defending champion Phil Mickelson carded a superb nine-under-par 62 to open up a four-stroke lead after the third round of the PGA Northern Trust Open at Riviera.
Mickelson looks well on course to retain his Riviera title after a third round 62 on Saturday.
The 38-year-old left-hander, who also led after the first round, eagled the opening hole for a second straight day before going clear of his rivals with four birdies in a row on the back stretch.
Mickelson, whose score was just one shot behind Ted Tryba's 1999 course record, lies on a 54-hole total of 197 (-16) -- well clear of Argentina's Andres Romero, who carded a six-under-par 65 for 201.
South Korea's KJ Choi, South African Rory Sabbatini, second-round leader Scott McCarron and Fred Couples are all tied for third place, five strokes behind Mickelson.
Mickelson, who won by two strokes in 2008, is one of three former champions among the top six on the leaderboard at Riviera. Couples won in 1990 and 1992 while Sabbatini won in 2006.