This qualitative exploratory study aims to investigate the pre-service English teachers’ perception and the challenges of ChatGPT as a generative AI tool to assisting in English academic writing. The participants were 9 seventh-semester students from the English Education Department at a university in Semarang, Indonesia. The participants were recruited based on four criteria: 1) pre-service English teacher who can run and use ChatGPT in writing, 2) have graduated from an academic writing course, 3) pre-service English teacher who are currently writing their theses, 4) have used ChatGPT as a tool to carry out their academic writing tasks. The data was collected through Google form questionnaires and interviews through Google Meet, then analyzed using thematic analysis based on aspect of TAM. The study revealed that pre-service English teachers generally have positive perception toward ChatGPT as a generative AI tool to assist in English academic writing with notable level of familiarity with its usage. However, there are some challenges identified in its implementation. Future researchers can examine the effectiveness of ChatGPT, its long-term impact, comparison with other AI tools, integration in the curriculum, and the ethical aspects.