David Ferrer believes that his tiredness let him down during the final of the Miami Masters on Sunday.
Ferrer, who at one stage was centimetres away from winning the championship on match point, admits that his fitness came into play towards the end of the match.
"I am tired. It was a very long match," Ferrer told Sky Sports News. "Andy had more at the end. Congratulations to him."
Ferrer has now lost all 12 of his duels with a top-four opponent.