Question: who was manager when chelsea won champions league
[{'answer': 'Roberto Di Matteo', 'provenance': [{'wikipedia_id': '4433351', 'title': 'List of Chelsea F.C. managers', 'start_paragraph_id': 1, 'start_character': 318, 'end_paragraph_id': 1, 'end_character': 335, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]