CREATE TABLE table_7587 ("Week" FLOAT, "Date" TEXT, "Opponent" TEXT, "Result" TEXT, "Attendance" FLOAT)

When did the Chargers play the Denver Broncos before Week 10?
SELECT "Date" FROM table_7587 WHERE "Week" < '10' AND "Opponent" = 'denver broncos'
SELECT "Date" FROM "table_7587" WHERE "Opponent" = 'denver broncos' AND "Week" < '10'