Justin Rose seized the lead in San Diego with a round of 66 on day two at the Farmers Insurance Open, while Rory McIlroy put in an scorching performance to rocket up the scoreboard.
World number one Rose stole the top spot from first round leader Jon Rahm and opened up a three-shot lead over Hideki Matsuyama in second.
A disappointing day saw Rahm card 72 and slip into tied third with Americans Ryan Palmer and Billy Horschel.
Rose picked up a string of shots with a birdie treble on holes four to six and made further gains before and after the turn.
More birdies on the 13th and 16th saw him arrive back at the clubhouse on 15-under overall and in a strong position ahead of the third round.
Former world-topper McIlroy pulled off the round of the day at Torrey Pines, notching two eagles and four birdies on an almost spotless round of 65.
The result saw the Northern Irishman ascend 65 places up the leaderboard into joint-ninth on eight-under, seven off the lead.
Scotsman Martin Laird also ended the day miles higher than where he began - a round of 66 propelling him 81 places upwards into 37th, where he is in the company of Englishman Danny Willett - who carded 68 - and 10 others.
Seamus Power followed up his opening 76 with a 78 that left him 10-over-par and ended his weekend early.