Crear un array de esta forma

[Jorge35]

prueba asi:

Código Javascript:

var doubleEliminationData = [];
doubleEliminationData .push({teams: [ ["team1","team2"] ]});
 

o de manera separada

Código Javascript:

var doubleEliminationData = {};
 
var teams = [];
teams.push(["team1","team2"]);
 
doubleEliminationData.teams = teams;