Before the COVID-19 pandemic, pre-service English as a Foreign Language (EFL) teachers (PSTs) experienced various forms of teaching anxiety. However, during the pandemic, they likely encountered additional, different types of teaching anxiety, especially at the teaching practicum stage. This study investigated factors causing anxiety in these PSTs prior to the practicum. It surveyed 257 PSTs from 10 polytechnic universities across Thailand scheduled to conduct a teaching practicum in the subsequent semester. The findings indicated that 246 PSTs (95.7%) had no prior experience with online learning. The PSTs reported being most familiar with Zoom and Google Meet, that these were the most convenient learning platforms, and also being most proficient in them. Two of their greatest concerns regarded online teaching, namely how they would do their practicum, e.g., hybrid, and what equipment and facilities schools would provide for them. Regarding anxiety, the participants demonstrated extremely high levels on four factors all associated with online teaching: the mode of instruction, whether online, onsite, or hybrid; the stability of the internet connection during online teaching; their teaching skills in the online mode; and their ability to integrate technological applications into their teaching. Given the participants' anxiety towards online teaching, pedagogical implications are discussed.