user: Question: What is the lowest Grid for JJ Lehto with over 51 laps?
Columns: ['Driver', 'Constructor', 'Laps', 'Time/Retired', 'Grid']
Types: ['text', 'text', 'real', 'text', 'real']
Sample row: ['Ayrton Senna', 'McLaren - Ford', 53.0, '1:40:27.912', 2.0]
SQL:

assistant: SELECT MIN("Grid") FROM "Table" WHERE "Laps" > 51.0 AND "Driver" = 'JJ Lehto';