CREATE TABLE table_10811 ("Round" TEXT, "Opponent" TEXT, "Date" TEXT, "Venue" TEXT, "Competition" TEXT)

what round saw wakefield trinity wildcats u21 as the opponenet at belle vue?
SELECT "Round" FROM table_10811 WHERE "Opponent" = 'wakefield trinity wildcats u21' AND "Venue" = 'belle vue'
SELECT "Round" FROM "table_10811" WHERE "Opponent" = 'wakefield trinity wildcats u21' AND "Venue" = 'belle vue'