Argentina star Juan Martin del Potro believes Croatia will begin the Davis Cup final as favourites after Thursday's draw.

Del Potro will face the giant Ivo Karlovic in Friday's second singles rubber after world number six Marin Cilic and Federico Delbonis get the tie under way in Zagreb.

With Croatia enjoying home-court advantage and two players inside the world rankings' top 20, Del Potro's assertion seems reasonable, but he says Argentina will scrap to win the Cup for the first time in their fifth final.

"We are hoping that this long quest for the cup title will come to an end," said Del Potro.

"They are at home and have a very strong team, but we are looking forward to a great weekend and we are also very proud to be in another final.

"I'll have to be focused against Karlovic because one break of serve could cost me the match.

"It is great to be in the final at this point of my career after so many injuries."

Across the net from Del Potro will be the oldest player to take part in a Davis Cup final singles match in almost a century.

Karlovic said: "Actually I don't know what to make of it. Is it good or is it bad? Maybe it is good, because my career was really long. That's why I'm still here!

"I would like to be a little bit younger, but this is life, we all have to get old one day. It's good that I'm still here."

Del Potro's return to form, after two years blighted by wrist injuries, has been a highlight of the ATP Tour in 2016 and he also beat both Novak Djokovic and Rafael Nadal en route to an Olympic silver medal in Rio.

"It will be a difficult match," said Karlovic of Del Potro, who he has beaten just once in five career meetings.

"He was doing unbelievable this year, how he played at the Olympics after his injuries. It will be a difficult match but I know that I will have my chances and I hope that I will be able to take them."

Cilic will be Croatia's star player and he admitted relief at being able to set the tone for his team against an opponent over whom he enjoys a 100 per cent record.

"I was hoping to start the tie," said Cilic. "I'm a favourite in that match against Federico but I still know that Federico is a great player. 

"We've played a couple of times so I know his game. We know what both of us are capable to do. If I can get the win it's going to be a little bit less pressure on Ivo and a little more pressure on Juan Martin."