ทัวร์นาเมนต์นี้เล่นกับสตีเวน ดิเอซบนพื้นผิวใด?
What surface was the tournament played on against Steven Diez?
df = pd.DataFrame(columns=['surface', 'opponent_in_the_final'])
df[df['opponent_in_the_final'] == 'Steven Diez']['surface']