Great Britain's Davis Cup final showdown against Belgium is at risk due to the threat of an imminent terrorist attack on Brussels.
The terrorists who killed 130 people in attacks in Paris are believed to have planned the atrocities in Molenbeek, a suburb of the Belgian capital.
Belgium's terror alert was raised to its highest level after weapons were discovered in the vicinity of Brussels, which closed down the city's metro service and postponed Anderlecht's clash against Lokeren.
There are now fears that the terror threat could cancel the Davis Cup final clash between Great Britain and Belgium in Ghent - 35 miles from the Belgian capital - due to security issues surrounding the event.
International Tennis Federation president David Hagerty said in a statement: "We are aware that Belgium has raised the terror alert level for Brussels. This greatly concerns us but, at the present time, we are still continuing with preparations for the final.
"What I said last weekend is true today: security of players, fans, media and working staff remains our highest priority."
The Davis Cup final begins next Friday.