user: Question: What is the highest number of the match with Julio César Vásquez as the opponent?
Columns: ['Number', 'Name', 'Titles', 'Date', 'Opponent', 'Result']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'Thomas Hearns', 'WBA Welterweight (147)', '1980-08-02', 'Pipino Cuevas', 'TKO 2/15']
SQL:

assistant: SELECT MAX("Number") FROM "Table" WHERE "Opponent" = 'Julio César Vásquez';