The Bears carded an opening round 16-under 334 in the six-count-five format and will take a one-stroke lead into Tuesday's second round over Oregon (-15) while Stanford (-11) is five off the pace.
Cal also benefitted from under-par rounds by Sampson Zheng (66), Jeewon Park (67), Daniel Heo (67) and a 1-over 71 by Nathan Wang.
Oregon nearly matched Cal shot-for-shot, carding a 15-under 335. Junior Gregory Solhaug is just one back of Du after carding an opening round 64 while Owen Avrit is two back after signing for a 65. Greyson Leach (68), Nate Stember (69) and Aiden Krafft (69) were also in red numbers for the Ducks.
Stanford's Michael Thorbjornsen shot a bogey-free 64 and along with Solhaug, is one back of Du heading into Tuesday's second round.
The final two rounds of the Western Intercollegiate will be carried live on Golf Channel. Tuesday's coverage begins at 4:00 p.m. PT with Wednesday's final round scheduled for 1:00 p.m. PT.
