nip and tuck

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adverb & adjective So close that the advantage or lead shifts from one to another and is virtually indeterminable.
• noun A cosmetic surgical procedure in which skin and usually fat are removed and muscle is sometimes tightened to create a slimmer or more youthful appearance.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective idiomatic so evenly matched that the advantage shifts from one to the other, and the outcome is uncertain
• adverb With the advantage changing hands.
• adverb dated With perceived advantage shifting back and forth among the available alternatives.
• noun minor cosmetic surgery that tightens loose skin

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective inconclusive as to outcome; close or just even in a race or comparison or competition
• adverb even or close in a race or competition or comparison
• noun 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