Table:
0
A
B
C
D
E
1
Outcome
Date
Surface
Opponent in the final
Score in the final
2
Runner-up
17 August 2008
Hard
Juan Martín del Potro
3–6, 3–6
3
Runner-up
4 October 2009
Hard (i)
Gilles Simon
5–7, 3–6
4
Winner
24 October 2010
Hard (i)
Marcos Baghdatis
3–6, 6–4, 6–3
5
Runner-up
15 January 2011
Hard
Gilles Simon
5–7, 6–7 (4–7)
6
Runner-up
23 October 2011
Hard (i)
Janko Tipsarević
4–6, 2–6

Questions and formulas:
Question: What was the surface on 23 October 2011?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,B1="23 october 2011"),3))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E6,B2:B6="23 october 2011"),3))
Level: medium