There are several antonyms that can be used for the phrase "new ball-game." Some common antonyms include "old hat," "same old thing," and "same routine." These phrases refer to something that is not new or exciting, but rather, something that is tedious, boring, or uninteresting. Other antonyms could be "predictable," "unchanged," or "status quo." These antonyms highlight the lack of change or innovation in a situation, which contrasts with the exciting, fresh start that a new ball-game represents. Ultimately, the antonyms for "new ball-game" convey a sense of familiarity and monotony, rather than enthusiasm and anticipation.