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:
| Date | Round | Opponent | Venue | Result | Attendance |
| --- | --- | --- | --- | --- | --- |
| 14 September 2004 | GS | Paris Saint-Germain | A | 3-0 | 40000.0 |
| 29 September 2004 | GS | Porto | H | 3-1 | 39237.0 |
| 20 October 2004 | GS | CSKA Moscow | H | 2-0 | 33945.0 |
| 2 November 2004 | GS | CSKA Moscow | A | 1-0 | 28000.0 |
| 24 November 2004 | GS | Paris Saint-Germain | H | 0-0 | 39626.0 |
| 7 December 2004 | GS | Porto | A | 1-2 | 42409.0 |
| 23 February 2005 | R2 | Barcelona | A | 1-2 | 89000.0 |
| 8 March 2005 | R2 | Barcelona | H | 4-2 | 42409.0 |
| 6 April 2005 | QF | Bayern Munich | H | 4-2 | 40253.0 |
| 12 April 2005 | QF | Bayern Munich | A | 2-3 | 59000.0 |
| 27 April 2005 | SF | Liverpool | H | 0-0 | 40497.0 |
| 3 May 2005 | SF | Liverpool | A | 0-1 | 42529.0 |
Question:
What is the round of the match at venue A with a result of 1-2 on 7 December 2004?
Answer:
GS