Britain overturned a 2-0 deficit in the Davis Cup for the first time in 83 years at the weekend as they defeated Russia 3-2 in the Europe/Africa Group I second round clash at the Ricoh Arena in Coventry.
Captain Smith's troops appeared to be heading to defeat after Dan Evans and James Ward were on the wrong side of five-set thrillers with Dmitry Tursunov and Evgeny Donskoy respectively.
However London 2012 Olympian Colin Fleming and Wimbledon doubles champion Jonny Marray defeated Igor Kunitsyn and Victor Baluda in straight sets to make it 2-1.
Ward, later to be placed on a drip to help him recover, was then on the right side of a five-set thriller with Tursunov before Evans saw off Donskoy in straight sets.
That completed a remarkable comeback for Britain and they now face a trip to Croatia, who lost to Italy 3-2 in round one of the 2013 World Group back in February, for the play-off.
World No.11 Cilic won both his singles rubbers against the Italians however Ivan Dodig lost his while as a doubles pair they couldn't overcome Simone Bolelli and Fabio Fognini.
And, with the winner contesting the 2014 World Group, Smith is once again full of belief that Britain can repeat their unlikely defeat of Russia when they face Croatia.
"Obviously Croatia is a tough draw and especially as it is an away tie," said Smith. "In Marin Cilic they have an extremely strong No.1 player who is currently ranked 11 in the world.
"Ivan Dodig is their current No.2 singles player and ranked at 54. But as we saw last weekend, anything is possible in Davis Cup."
Britain last faced Croatia in the Davis Cup at Wimbledon in September 2007 where they ran out 4-1 winners in Tim Henman's last outing before retirement.
Croatia have until the end of the month to decide on a venue and a surface on which to host the September tie.