The Great Britain team were preparing to travel to Belgium on Monday ahead of the Davis Cup final despite the terror threat in Brussels remaining at its highest level.
Captain Leon Smith and his players had been due to fly to the Belgian capital on Sunday, but by lunchtime had delayed their departure by a day because of the security situation there.
On Sunday evening, Belgian prime minister Charles Michel announced the threat level in the Brussels area would stay at category four on Monday.
It was raised on Saturday because of a "serious and imminent" threat of a Paris-style attack. The city's Metro system has been shut all weekend and will be staying closed on Monday, along with schools and universities.
Ghent, where the Davis Cup final is being held starting on Friday, is only 35 miles from Brussels and t he 13,000-seat Flanders Expo is sold out for all three days of the final, with more than 1,000 British fans due to attend.
International Tennis Federation president David Haggerty said on Saturday he was "greatly concerned" by developments, but that preparations for the tie would continue.
Former British number one Tim Henman, though, has cancelled his plans to attend the final.
He was quoted as saying by several national newspapers: "I was going to go, but I am not going any more.
"I was going to take the three girls, I was going to go with my family. With the train and the going over there, I just thought, 'Is it really worth the hassle for them?'
"So we are going to be watching at home."
Meanwhile, Novak Djokovic headed off for a well-earned holiday after ending a season "as close to perfection as it can get" with his 11th title of 2015 at the ATP World Tour Finals.
Djokovic's 6-3 6-4 victory over Roger Federer made him the first man ever to win the season-ending tournament four times in a row and left one of his biggest rivals where they have all been this year, trailing helplessly in his wake.
The result also means Andy Murray is guaranteed to finish the year ahead of Federer at world number two for the first time.
Had Djokovic won the French Open, there would surely be no argument about it being the best season in tennis history.
The only tournament in which he did not reach the final was his first of the season and his haul included three grand slams and six Masters series trophies.
At 28, Djokovic already has 10 grand slam titles, seven short of Federer's record - and worryingly for the rest, there is no sign that his appetite is sated.
The Serbian said: "It's been a great year with many highlights. If I can, I would pick obviously grand slam wins, especially Wimbledon and the US Open. I think this tournament, as well.
"Overall it's been as close to perfection as it can get.
"I'm just blessed and overwhelmed with the emotion and the thrill to be achieving such a great season. It inspires me even more to keep on going and hopefully playing on this level in the future.
"I'm convinced with this dedication to the sport, I can achieve more. How much, I don't know."