But he 's still the favorite to win the tournament , with Murray and Djokovic . ` Juan Martin del Potro beats Del Potro to claim semifinal place in ATP World Tour Finals . Argentine 's one -set victory ends the hopes of Spain 's world No . 5 David Ferrer . Ferrer finishes on a high note as he beats Andy Murray in final round-robin match . Federer will face Juan Martin del Potro in 2009 's semifinals , while Del Potro plays Novak Djokovic .
Juan Martin del Potro beats Del Potro to claim semifinal place in ATP World Tour Finals . Argentine 's one -set victory ends the hopes of Spain 's world No . 5 David Ferrer . Ferrer finishes on a high note as he beats Andy Murray in final round-robin match . Federer will face Juan Martin del Potro in 2009 's semifinals , while Del Potro plays Novak Djokovic .