user: Question: What is the zone of the game played against Estonia?
Columns: ['Edition', 'Zone', 'Round', 'Date', 'Against', 'Surface', 'Partner', 'Opponents', 'Result']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [2004.0, 'Europe/Africa Group I', '1R', '20 April 2004', 'Lithuania', 'Clay', 'Dragana Zarić', 'Edita Liachovičiūtė Lina Stančiūtė', 'Win 7–5, 6–3']
SQL:

assistant: SELECT "Zone" FROM "Table" WHERE "Against" = 'Estonia';