CREATE TABLE table_54613 ("Stage" FLOAT, "Date" TEXT, "Course" TEXT, "Distance" TEXT, "Winner" TEXT, "GC Leader" TEXT)

Who is the GC leader at vila - segovia?
SELECT "GC Leader" FROM table_54613 WHERE "Course" = 'ávila - segovia'
SELECT "GC Leader" FROM "table_54613" WHERE "Course" = 'ávila - segovia'