Great Britain captain Jeremy Bates pointed to the lack of depth in his squad after the Davis Cup defeat to Serbia & Montenegro.
Bates was without top player Andy Murray on the opening day
Bates said he was "disappointed" to lose the Euro-Africa Zone tie after Novak Djokovic's win over Greg Rusedski gave the visitors an unassailable lead.
But he told BBC Sport: "We've got to find some other avenues, new players to take the pressure off Greg."
Britain now face a relegation play-off against Israel in July.
And Bates admitted he was frustrated that illness meant British number one Andy Murray had been forced to miss the opening day's singles.
"We're disappointed," said Bates. "We've had a good week of preparation but we haven't had a lot of luck.
"Andy (Murray) would have come out and played this afternoon, against advice, and I can't criticise anybody's application and commitment."