Table: chelsea_season_1996_97
Columns: date
round
opponent
venue
result
attendance
scorers

Question: What team was the opponent when the round was sf?
SQL: SELECT "opponent" FROM chelsea_season_1996_97 WHERE "round" = 'sf'

Question: What is the number of people in attendance when venue shows A, and Di Matteo, M. Hughes were the scorers?
SQL: SELECT SUM("attendance") FROM chelsea_season_1996_97 WHERE "venue" = 'a' AND "scorers" = 'di matteo, m. hughes'