Tsonga, Cilic, Querrey: US Open Dark Horses in the Making

dark horse   n.  1.    One who achieves unexpected support and success as a political candidate, typically during a party's convention.2.    A little-known, unexpectedly successful entrant, as in a horserace.                                                                                      -- Dictionary.com A "dark horse" is a term used to describe a little-known person or thing that emerges to prominence.                     ...