Thompson has the 36-hole lead thanks to a birdie on the final hole for a 6-under 66, but top-ranked Scottie Scheffler is one stroke back and Rory McIlroy is three shots behind at Torrey Pines.
Needing to fill the void created by Anthony Davis' trade to Dallas for Luka Doncic, the team will bring in the 7-footer while waiving injured Christian Wood.
Zachary Visentin scores a career-high 17 points, but the Titans shoot 29.8% and turn the ball over 22 times in a 65-49 defeat, dropping to 6-19 overall and 1-11 in Big West play.
Former Laker Anthony Davis had 26 points, 16 rebounds, seven assists and three blocked shots before leaving in the third quarter while Max Christie scored 23.
Anthony Davis went back to the locker room in his debut with the Dallas Mavericks after sustaining an injury late in the third quarter Saturday against Houston.
Anthony Davis caused some concern among Dallas Mavericks fans after exiting his franchise debut Saturday against the Houston Rockets with a lower-body injury.