nip and tuck

American Heritage® Dictionary of the English Language, Fourth Edition

1. adv. So close that the advantage or lead shifts from one to another and is virtually indeterminable.

Wiktionary

1. adj. idiomatic so evenly matched that the advantage shifts from one to the other, and the outcome is uncertain
2. adv. With the advantage changing hands.
3. adv. dated With perceived advantage shifting back and forth among the available alternatives.
4. n. minor cosmetic surgery that tightens loose skin

GNU Webster's 1913

1. n. [Low, U.S.] a phrase signifying equality in a contest.

WordNet 3.0

1. adj. inconclusive as to outcome; close or just even in a race or comparison or competition
2. adv. even or close in a race or competition or comparison
3. n. plastic surgery to remove wrinkles and other signs of aging from your face; an incision is made near the hair line and skin is pulled back and excess tissue is excised