Belgrade: Novak Djokovic was forced to withdraw from the opening day of the Davis Cup World Group semi-final between Serbia and Czech Republic on Friday due to stomach problems, a statement said.
Victor Troicki, world ranked 47, will replace Djokovic in the first rubber against Czech Radek Stepanek, ranked 35th, a statement on the Davis Cup website said.
It was unclear whether Serbia`s top player, who had only returned from US Open early on Wednesday where he lost in the final to Rafael Nadal, would be able to play in a singles match on Sunday.
Serbia`s Tennis Association officials were not available for comment.
Serbia`s team was impressive in the Davis Cup this season, defeating the United States 3-2 in Belgrade and then cruising past Croatia 4-1 in the quarter-finals in Split.