Zadar - The United States cut Croatia's lead to 2-1 in their Davis Cup semi-final as Mike Bryan and Ryan Harrison won a dramatic doubles rubber in Zadar on Saturday.
Croatia, who saw Marin Cilic and Borna Coric both win their singles matches on Friday, will try again on Sunday to book a final date with defending champions France in November.
Bryan and Harrison won a deciding-set tie-break to end a thrilling comeback from Ivan Dodig and Mate Pavic with a 7-5, 7-6 (8/6), 1-6, 6-7 (5/7), 7-6 (7/5) victory after four hours and 43 minutes on court.
But Croatia captain Zeljko Krajan is still confident that his team will secure victory in Sunday's first match which sees world number six Cilic face Steve Johnson.
"Cilic is a big favourite... it will definitely not be easy to defeat him in front of a home crowd," Krajan told television channel HRT.
If Johnson causes an upset against Cilic, Coric will play against Davis cup debutant Frances Tiafoe in a deciding rubber.
On Friday, Coric justified his favourite's tag and defeated Johnson 6-4, 7-6 (7/4), 6-3, before Cilic defeated Tiafoe 6-1, 6-3, 7-6 (7/5) to leave his country on the brink of the final.
Croatia have made the final twice, in 2005, when they were crowned champions, and 2016.
Croatia have beaten the USA on each of their four previous Davis Cup meetings.
Jim Courier's team is missing two top players - John Isner, the world number 10 who has stayed home due to family reasons, and injured Jack Sock.
France took an unassailable 3-0 semi-final lead over Spain earlier on Saturday to secure a 19th final appearance.