Andrew Landry carded a seven-under-par 65 to take a one-shot lead at the CareerBuilder Challenge following Friday's second round.
Playing the year's first PGA Tour event on the mainland, Landry birdied five of his last eight holes to take the lead entering the weekend at 16 under.
The American has not yet made a bogey this week as he leapfrogged Jon Rahm atop the leaderboard.
Spanish star and world number three Rahm finished round two just one shot back after firing a 67.
Rahm already has a runner-up finish this year. He had two early bogeys on Friday, but settled down on the back nine.
Jason Kokrak ended the second round in third place at 14 under following his 69 after his impressive nine under opening round.
"I worked with my coach and was struggling in a practice round on Wednesday," Kokrak said Friday. "My legs get a little bit too jumpy and move around a lot. So we worked on that and I started hitting the ball pretty good and I'm just trusting it out there.
"I've given myself a lot of close opportunities. I rolled the putter very well [Thursday] and [Friday] didn't make quite as many, but still gave myself a lot of chances."
Zach Johnson surged up the leaderboard with an eight-under 64. The two-time major champion had six birdies on his back nine to climb into a tie for fourth at 13 under alongside Michael Kim (64) and Martin Piller (67).
Brian Harman, in search of his sixth straight top-eight finish, shot a four-under 68 to remain in the hunt at 11 under.
He had just one bogey on day two, but did not give himself as many birdie opportunities as he did on Thursday.
Defending champion Hudson Swarfford (68) is six shots off the pace heading into Saturday's third round, while two-time Masters winner Bubba Watson (71) is three under.
|Messi: I´d give up Barca title for World Cup glory|
|LeBron reaching eight straight Finals is ridiculous and unbelievable – Stevens|
|Indians top Astros in 14 innings as Cole-Bauer duel turns into marathon|
|I´m squeezing this orange until there´s no juice left – LeBron|
|LeBron James leads Cavs past Celtics and into NBA Finals|
|Kyle Busch dominates to win Coca-Cola 600|
|Henderson still confident of Liverpool success|
|Sporting Kansas City 0 Columbus Crew 0: 10-man visitors battle to MLS draw|
|Inglis to captain new-look Maroons, Boyd and Scott axed for Origin I|
|Neymar labels Real Madrid links ´nonsense´|
|Koepka ready to turn seconds into wins|
|Rose ´really proud´ of Fort Worth Invitational win|
|Paul a ´game-time decision´ for series decider, says Rockets coach D´Antoni|
|Egypt president wishes Salah speedy recovery|
|Bonucci: Balotelli has matured|
|Ranieri backs Sarri to succeed at Chelsea|
|Konta admits to doubts after another early Roland Garros exit|
|Warriors´ Iguodala, Looney listed as questionable for game seven|
|Zverev batters Berankis, Goffin back from the brink in Paris|
|Rose cruises to victory at Colonial|
|Neymar: I´m not at 100 per cent yet|
|Toulouse confirm Ligue 1 survival with win over Ajaccio|
|I know what I´ve achieved - Bale not worried about plaudits as he looks to the future|
|Ostapenko ´angry´ after Roland Garros exit, Venus Williams falls at first hurdle|
|Barcelona B relegated to Spain´s third tier|
|Rayo Vallecano win promotion to LaLiga|
|Tarkowski leaves England camp for hernia surgery|
|Ramos ´quite clever´ but Salah injury not to blame for final defeat, insists Robertson|
|WATCH: Ricciardo takes wide receiver role on yacht for Tom Brady pass|
|Until next year – Ronaldo drops new future hint as Real Madrid celebrate with fans|
|Froome stunned by Giro triumph|
|The Triple Crown: Froome´s Grand Tour glory in numbers|
|Hannover sign Wimmer on season-long loan|
|Inter powerless to stop Icardi exit, admits Spalletti|
|Ashton makes England statement with Barbarians hat-trick|
|Watson masterclass seals third IPL title for Super Kings|
|Kozlova ends Ostapenko´s Roland Garros reign on day one|
|Imperious Zverev breezes into second round|
|Froome wins Giro d´Italia to complete Triple Crown|
|Stricken Salah confident over World Cup hopes|
|Verstappen highlights change in approach amid Rosberg criticism|
|Strinic claims three-year deal at Milan|
|Napoli captain Hamsik considering China offer|
|Chinese outsider Wang shocks Venus Williams in Paris|
|Redemption two years in the making - Ricciardo revels in Monaco glory|
|Flawless Molinari holds off McIlroy at Wentworth|
|Karius ´infinitely sorry´ but thanks Liverpool fans for support|
|Root and Bayliss dismiss ´outrageous´ fixing allegations|
|Giggs: Bale the best Welsh player I´ve seen|
|Ricciardo ends Monaco hoodoo despite mechanical issue|
|Lyon star Fekir denies being close to Liverpool switch|
|Pogba: I learned a lot from Abou Diaby|
|Where next for Real Madrid stars Ronaldo and Bale?|
|Shingler and Hewitt out of Wales tour|
|Kyrgios pulls out of French Open|
|Khan wants to bow out by winning blockbuster Brook fight|
|Is winter coming? Game of Thrones stars descend on Monaco|
|Root urges England´s batsmen to ´find a way´|
|Lovren, Van Dijk absolve Karius of blame|
|We all know where our nipples are - Hansen welcomes tackle trial|
|Rooney would thrive in MLS, says DC United boss|
|Pakistan complete demolition of sorry England|
|Curry, Durant reveal the secret to Thompson´s success|
|Salah will miss World Cup, claims Saudi sports administrator|
|Deschamps marvels at Zidane´s incredible Champions League success|
|FIA satisfied Ferrari ´inside the rules´|
|NSW Origin hopeful Moylan pulls the strings for rampant Sharks|
|Champions League blunders will stay with Karius - Clemence|
|Warriors assuming Iguodala won´t play game seven, Kerr says|
|Lampard confirms Derby talks over vacant managerial position|