Simona Halep, who was knocked out of WTA Finals round-robin event after losing to Agnieszka Radwanska, admits that after losing the first set she was done both emotionally and physically.

The world No. 2 rank was up 5-1 in the first-set tiebreak, but fell 7-6 (5), 6-1.  
“I was done. No energy anymore,” she said. “I was tired. I felt that I lost the chance to win the first set and probably I lost the chance to win the match in that moment. My coach was telling me many things, but I couldn't hear because I was done and I was very nervous there."  
Halen, who is coached by Darren Cahill, said that she was also dealing with an Achilles heel injury and added that if she had won the first set, she may have had more energy in the second set.  
“Maybe. Because if I would win that tiebreak maybe mentally I would be stronger,” she said. “Now that I lost it, I went down also with my mental [strength].”