Also matchplay, match -play.
1. Chiefly British: Competitive play in matches with standings consequences, such as local snooker league competition or the World Snooker Championship, as opposed to practice, playing with friends at the pub, or hustling pool for money.
2. Chiefly American: Same as one-on-one as applied to league play. (Definition appears to have been introduced by USA Pool League misapplying the term "match" to what is otherwise termed a "race".)