However, should Del Potro extend the tie 37-year-old Karlovic-the oldest player to feature in a Davis Cup singles match since 43-year-old Australian Norman Brookes in 1920-and Delbonis would then face off in the deciding rubber.
The Argentines have not brought home a notable trophy since their historic win in the FIFA World Cup 1986. Still, Argentina also had its part of support with hundreds of Argentine fans in the stands. They come in numbers to support their country, in a hope to return with memories for a lifetime.
Best fans of the day: Argentina.
The Davis Cup final of 2016 was a sporting contest with "first time" and "never before" at every turn. This is Davis Cup'. But the outcome was no different, a loss at the end was written in their destiny too.
Commenting specifically on Del Potro's stunning success, which left the former U.S. Open champion on the verge of tears, Orsanic added: "His comeback is the comeback of the history - it's the comeback of the Davis Cup".
The popular Argentine began the year ranked outside the top 1,000, and was once again attempting to make his way up the ladder after his fourth bout of wrist surgery.
"It was a really tough decision to take Borna off the team", Krajan said, per the Davis Cup website.
This was Argentina's fifth time to play in the finals since 1981.
Federico Delbonis (ARG) waves to the crowd in March 2016.
After Del Potro's win, Delbonis played calmly and prevailed over Karlovic in straight sets in about two hours.
Quite how it has taken one of the modern-day powerhouses of the game so long to win tennis' ultimate team prize is certainly not a question Del Potro will be answering today. Considering that even Diego Maradona wanted to revel in the experience of seeing his country win, it should not be a hardship for the ITF to ensure the sanctity and singularity of the one-of-a-kind tournament remains intact, unaffected by its own seemingly mercenary aspirations.
That win, like Sunday's team victory against Croatia, was the sort of unprecedented stuff that was predicted for Del Potro when he was a younger man. When Marin Cilic was two sets to love up, it looked as if Croatia were on the brink of a special victory in their home of Zagreb, but Del Potro stormed back into the match to keep the tie alive. His teammates fell on him as the moment had arrived - Argentina had done it.