user: Question: Who played in the semi finals matches at the Buick WCT Finals?
Columns: ['Date Final', 'Tournament', 'Commercial Name', 'Category', 'Prize Money/ Surface', 'Final Match', 'Semifinal Matches']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Mar 3', 'Houston , USA', 'WCT Houston Shoot-Out', 'Nabisco Grand Prix', '$300,000 Carpet', 'John McEnroe d. Kevin Curren , 7–5, 6–1, 7–6', 'John McEnroe d. Peter Fleming , 6–4, 6–0']
SQL:

assistant: SELECT "Semifinal Matches" FROM "Table" WHERE "Commercial Name" = 'Buick WCT Finals';