Brazilian teenager Joao Fonseca stunned top seed and 2023 runner-up Arthur Fils with a five-set victory in his NextGen ATP Finals opener on Wednesday. Elsewhere in the Blue Group on Wednesday, 122nd-ranked Learner Tien of the United States upset Czech world number 48 Jakub Mensik 4-3, 4-3, 2-4, 2-4, 4-3. “I think the experience of last year helped me a …
