ACE. Squeaking sneakers during play. Audible evidence of a tennis player's need for good footwork.
ACE. The face-to-face sideways shuffle that doubles partner Leander Paes and Radek Stepanek performed after scoring big points. It's more creative than the Bryan twins' chest bumps.
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ACE. The classic old one-handed backhand. Ye Olde Tennis Shot has helped produce two quarterfinal upsets in men's play, Richard Gasquet over David Ferrer and Stanislas Wawrinka over Andy Murray.
FAULT. Really loud "Fault!'' calls by linespeople admirably doing their jobs are informative. But it seems to add insult to injury to the player who has just botched a shot.
By the numbers
20-1 Rafael Nadal's hardcourt match won-lost record in 2013.
38-1 Victoria Azarenka's hardcourt match won-lost record since she lost to Serena Williams in last year's Open final.
1.000 Andy Murray's winning percentage in night matches at the Open. (Equaled only by Pete Sampras.) But he played -- and lost -- in the sunshine Thursday.
The tennis players' sign language: A nod is calling for a ball from the ballpersons. A hand wiping in front of the face is calling for a towel. A raised finger, or raised racket, toward the chair umpire is calling for a challenge review.