user: Question: How many combination classifications have the winner as Erik Zabel and a points classification as Alessandro Petacchi
Columns: ['Stage', 'Winner', 'General classification', 'Points classification', 'Mountains classification', 'Combination classification', 'Team classification']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'ONCE-Eroski', 'Igor González de Galdeano', 'Igor González de Galdeano', 'Jan Hruška', 'Igor González de Galdeano', 'ONCE-Eroski']
SQL:

assistant: SELECT COUNT("Combination classification") FROM "Table" WHERE "Points classification" = 'Alessandro Petacchi' AND "Winner" = 'Erik Zabel';