The phrase "an unknown player" is correct and usable in written English.
It can be used when referring to a player whose identity or skill level is not recognized or established, often in the context of sports or games.
Example: "In the tournament, an unknown player surprised everyone by defeating the reigning champion."
Alternatives: "a mysterious player" or "an unidentified player".
"I'm an unknown player in Botswana," breezed Bobby to the country's media, although he declined to add that he is an unknown player at Wimbledon too.
"In Eredivisie measures, it was as if a superstar had arrived because usually the type of player that joins the league is a either a promising talent or an unknown player.
If Central Casting (or Central Intelligence) had searched for an unknown player to explain the challenges of a reborn Afghanistan to the United States and the world, it could hardly have done better than Mr. Karzai.
Her prize money from this year's tour, which she started as virtually an unknown player, will total $29,000, and soon it is expected to go to more than $85,000 a year.
A world-wide field attempts to qualify and until global television coverage of golf developed recently, you could be assured of an unknown player from a lesser-known tour far away grabbing the spotlight at least for a moment.
Asian-American Jeremy Lin of the New York Knicks went from an unknown player to the star of the league when given a chance to contribute, and his popularity stretched from New York to China to Taiwan.
RSL will be ready, no matter the lineup as the match is already close to a sell out and with FC Dallas also missing a number of key players due to injuries and suspensions this could be a match where a fairly unknown player for either team could make a huge impact.
The clutch home run off Papelbon evoked Mets memories of Omir Santos, a similarly unknown player who hit a game-winner into the stands at Fenway Park off Papelbon in 2009.
If you're looking for a largely unknown player who could make a huge splash at the tournament, Franck Ribery of Marseille has yet to make his debut for the national team, yet he appears to be as naturally talented as Michel Platini.
At the conclusion of his entry-level contract in 2011, Turris and the Coyotes were unable to come to terms on a new deal, and he eventually requested a trade, even though he was a relatively unknown player at the time.
A relatively unknown player, GameFace Labs, recently revealed at CES their plans to create an untethered virtual reality headset that does not need a PC to operate.
