user: Question: Who won the young rider classification in Stage 9 where the mountain classification was Emanuele Sella?
Columns: ['Stage', 'Winner', 'General classification', 'Points classification', 'Mountains classification', 'Young rider classification']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'Slipstream-Chipotle', 'Christian Vande Velde', 'no award', 'no award', 'Chris Anker Sørensen']
SQL:

assistant: SELECT "Young rider classification" FROM "Table" WHERE "Mountains classification" = 'Emanuele Sella' AND "Stage" = 9.0;