user: Question: What is the round when Grand Slam was the Davis Cup?
Columns: ['Year', 'Grand Slam', 'Round', 'Winner', 'Loser']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1968.0, 'French Open', 'First round', 'Nikola Špear', 'Daniel Contet']
SQL:

assistant: SELECT "Round" FROM "Table" WHERE "Grand Slam" = 'Davis Cup';