user: Question: Who were the semifinalists when the runner-up was Pat Du Pré?
Columns: ['Week of', 'Tournament', 'Champion', 'Runner-up', 'Semifinalists', 'Quarterfinalists']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['6 November', 'Stockholm , Sweden Hard – $175,000 – S64/D32', 'John McEnroe 6–2, 6–2', 'Tim Gullikson', 'Björn Borg Wojtek Fibak', 'Peter Fleming Tom Okker Arthur Ashe Stan Smith']
SQL:

assistant: SELECT "Semifinalists" FROM "Table" WHERE "Runner-up" = 'Pat Du Pré';