CREATE TABLE table_6307 ("Res." TEXT, "Record" TEXT, "Opponent" TEXT, "Round" FLOAT, "Time" TEXT, "Location" TEXT)

What is the round number of the match with Michael Buell as the opponent?
SELECT "Round" FROM table_6307 WHERE "Opponent" = 'michael buell'
SELECT "Round" FROM "table_6307" WHERE "Opponent" = 'michael buell'