The phrase "catches off guard" means to surprise or startle someone. Antonyms for this phrase could include "prepared," "expecting," or "forewarned." These words convey a sense of readiness or awareness, indicating that the person is not caught off guard. Other antonyms might include "anticipating," "alert," or "mindful." In any case, the opposite of being caught off guard implies a state of being attentive and aware, rather than caught unawares. By using these antonyms, we can convey a sense of preparedness and mindfulness, rather than vulnerability to unexpected events.