What is the test for abuse of abuse of power under section 945.4?

[117 Cal.App.3d 726] Rivera argues that abuse of discretion is shown because the city failed to prove that it would be prejudiced if he were relieved from the claim-filing requirement of section 945.4. The contention lacks merit. The city had no burden to establish prejudice until Rivera had satisfied the court that his failure to file a timely claim was due to mistake, inadvertence, surprise or excusable neglect. (Tammen v. County of San Diego, supra, 66 Cal.2d 468, 478, 58 Cal.Rptr. 249, 426 P.2d 753; Hasty v. County of Los Angeles (1976) 61 Cal.App.3d 623, 627, 131 Cal.Rptr. 347; Black v. County of Los Angeles (1970) 12 Cal.App.3d 670, 677-678, 91 Cal.Rptr. 104.)