Dominic Thiem has stormed into the semi-finals of the ATP Finals.
He's become the first player to qualify for the final four after upsetting Novak Djokovic in three sets.
Meanwhile, seven-time Dubai Duty Free Tennis Championships winner Roger Federer returned to winning ways with a straight-sets win over Matteo Berrettini.
That means he'll now take on Djokovic for a spot in the semi-finals.


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