CREATE TABLE table_34521 ("Team 1" TEXT, "Agg." TEXT, "Team 2" TEXT, "1st leg" TEXT, "2nd leg" TEXT)

What was the 1st leg of the match that had an aggregate of 4-3?
SELECT "1st leg" FROM table_34521 WHERE "Agg." = '4-3'
SELECT "1st leg" FROM "table_34521" WHERE "Agg." = '4-3'