Juan Martin del Potro showed few signs of being slowed by an injured left wrist, defeating Radek Stepanek 6-4, 6-4, 6-2 Friday to give Argentina a 1-0 lead against the Czech Republic in their Davis Cup semifinal.

Del Potro, who was told by doctors not to play with the inflamed wrist, broke the Czech in the ninth game of the first set. The former U.S. Open champion broke Stepanek twice in the second and third set and got stronger as the match went on.

However, Del Porto broke down in tears while speaking to the crowd after the match.

"In truth, it wasn't easy to play," said the right-handed Del Potro as the crowd chanted "Ole, Ole, Ole."

Czech Tomas Berdych faces Juan Monaco in second singles on Friday.