This research seeks to investigate the influence of lesson study on preservice secondary mathematics teachers' view of self as mathematics expert. The study acknowledges the commonly held belief that prospective mathematics teachers have that they know and understand secondary mathematics. The purpose in engaging the preservice teachers in lesson study is to dislodge this belief. In particular, this research report focuses on one preservice teacher and her experiences during lesson study. Using the data collected, the researcher reports on the baseline beliefs that the preservice teacher held toward her knowledge of secondary mathematics, her mathematical experiences during the actual lesson study phase of the research and the final status of her beliefs in relation to her secondary mathematics understanding. After assessing the preservice teacher's beliefs, the report focuses on the moves the preservice teacher makes to protect her identity as a knower of mathematics. The report details how the researcher probed the subject's views through a follow-up interview. The researcher discovered during the follow-up interview that the subject was finally able to admit her lack of mathematical knowledge and her desire to not be seen as 'dumb' in front of the interviewer. The implications of the study suggest that teacher educators should be sensitive to preservice secondary teachers' perceptions of their mathematical knowledge and teacher educators should watch for the moves preservice teachers make to shift conversation away from mathematics topics.