Question: What ground had Portsmouth Reserves as an opponent?
SQL: SELECT "Ground" FROM "2-18539546-18" WHERE "Opponent" = 'Portsmouth Reserves';

Question: What ground had a match smaller than 6 and Chelsea Reserves as the opponent?
SQL: SELECT "Ground" FROM "2-18539546-18" WHERE "Match" < 6.0 AND "Opponent" = 'Chelsea Reserves';