The phrase "being neck and neck" is commonly used to describe a situation where two or more parties are in a closely contested race or competition. Antonyms for this phrase would be "one-sided," "uneven," "lopsided," or "unequal." These words all suggest a situation where one party has a significant advantage over the other(s). Another antonym could be "far behind," indicating a large gap between the parties involved. In contrast, synonyms for "being neck and neck" would include phrases like "tied," "evenly matched," or "not a hair's breadth between them," all describing a close competition with little difference between the parties involved.