Heavy rain halted play just three games into Great Britain's Davis Cup quarter-final against Serbia in Belgrade.
Britain's Kyle Edmund - leading the team in the absence of Wimbledon champion Andy Murray - led Janko Tipsarevic in the opening singles rubber when the covers came on.
World number 67 Edmund, 21, held serve twice to lead the two-time US Open quarter-finalist 2-1.
James Ward will play Dusan Lajovic in Friday's second singles rubber.