Antonyms for the phrase "catch off guard" could include "prepare for," "foresee," "expect," "anticipate," "be vigilant," "be wary," "be watchful," and "be alert." These terms convey a sense of being ready and aware, rather than being caught unawares. Another antonym for "catch off guard" could be "miss the opportunity," indicating that one is late to take advantage of a situation instead of being surprised by it. It is important to keep in mind that being caught off guard can be a positive or negative experience depending on the circumstances, so the best antonym will depend on the specific context.