Jack Crook scored five straight Seattle points in the first two minutes of the extra session for a 73-70 lead. Darius Graham made a 3 with 47 seconds left to cut the Redhawks' lead to 77-75, but Malik Montoya responded with a layup with 22 seconds left.
Graham missed a 3 on UC Davis' next possession and Brendan Westendorf made 1 of 2 from the line for a five-point lead.
Seattle (6-7) trailed 61-59 with under five minutes left in regulation, but Clair hit three 3-pointers in the last four minutes for a 68-65 lead with 46 seconds left. Nine seconds later, Siler Schneider tied it with a 3 to force overtime.
Josh Fox led UC Davis (4-7) with 18 points.