The phrase "am a match for" conveys a sense of equality or strength in one's abilities. Some antonyms for this phrase could be "inferior to," "unmatched by," or "outmatched." These antonyms suggest a lack of skill or power in comparison to another entity. Other possible antonyms could include "outclassed," "overpowered," or "outperformed," implying that the individual is unable to keep up with or perform as well as their opponent. Additionally, words such as "inadequate," "insufficient," or "weak" could be used to indicate a lack of capacity or ability to compete effectively.