Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Week | Date | Opponent | Result | Attendance |
| --- | --- | --- | --- | --- |
| 1.0 | September 9, 2001 | Tampa Bay Buccaneers | L 10–6 | 61,521 |
| 2.0 | September 23, 2001 | San Diego Chargers | L 32–21 | 63,430 |
| 3.0 | September 30, 2001 | at Philadelphia Eagles | L 40–18 | 66,621 |
| 4.0 | October 7, 2001 | at Oakland Raiders | L 28–21 | 61,535 |
| 5.0 | October 15, 2001 | Washington Redskins | W 9–7 | 63,941 |
| 6.0 | Bye | Bye | Bye | Bye |
| 7.0 | October 28, 2001 | Arizona Cardinals | W 17–3 | 63,114 |
| 8.0 | November 4, 2001 | at New York Giants | L 27–24 | 78,673 |
| 9.0 | November 11, 2001 | at Atlanta Falcons | L 20–13 | 69,010 |
| 10.0 | November 18, 2001 | Philadelphia Eagles | L 36–3 | 63,204 |
| 11.0 | November 22, 2001 | Denver Broncos | L 26–24 | 64,104 |
| 12.0 | December 2, 2001 | at Washington Redskins | W 20–14 | 85,112 |
| 13.0 | December 9, 2001 | New York Giants | W 20–13 | 61,821 |
| 14.0 | December 16, 2001 | at Seattle Seahawks | L 29–3 | 63,366 |
| 15.0 | December 23, 2001 | at Arizona Cardinals | L 17–10 | 48,883 |
| 16.0 | December 30, 2001 | San Francisco 49ers | W 27–21 | 64,366 |
| 17.0 | January 6, 2002 | at Detroit Lions | L 15–10 | 77,512 |
Question:
Who was the opponent before week 5 that played on September 23, 2001?
Answer:
San Diego Chargers