Japan picked up the first point of the day when Go Saeda made a stunning rally for a 6-7 (3-7), 3-6, 6-4, 6-3, 7-5 victory over Ivan Dodig, but Ivo Karlovic quickly halted the host nation's momentum with a 6-4, 6-4, 6-3 triumph over Kei Nishikori.
The best-of-five will continue on Saturday with the doubles match that is scheduled to feature the Japanese tandem of Tatsuma Ito and Yuichi Sugita versus a Croatian duo of Karlovic and Lovro Zovko, while Sunday's reverse singles currently call for Nishikori to battle Dodig and Karlovic to take on Soeda.
Dodig appeared to have control of the opening match, as he raced out to a 4-0 lead in the first-set tiebreaker and picked up a late break of serve in the second set.
Soeda, though, broke Dodig in the 10th game to win the third set and carried the momentum into the fourth by winning the first three games. After Dodig broke back in the fifth game, Soeda broke serve again for 4-2 and went on to square the match.
Each player broke serve once midway through the fifth set, which went to 5-5 before Soeda set up another break point with a backhand. Dodig then sent a forehand long and Soeda cemented the incredible comeback with a hold at love in the final game of the more than four-hour match.
"I think it was my best win ever," said Soeda, who also beat Dodig last month in the second round of the Chennai Open en route to a semifinal appearance.
Karlovic, much like Dodig, also won the first two sets in the second match of the day, but he didn't allow Nishikori a chance to get close. He closed out the third by winning the final four games with a pair of breaks.
"I tried to mix a lot and not rally a lot with him," said Karlovic, who used his booming serve to his advantage. "I try to win as quickly as I can on every point and I was trying to be as aggressive as I could."
The 6-foot-10 Karlovic banged out 18 aces and didn't face a break point during the match. Nishikori won a mere 12 points on Karlovic's serve.
Team Croatia is captained by Zeljko Krajan, while Japan is led by Eiji Takeuchi. This marks the first-ever meeting between the two nations.
Croatia captured its lone Davis Cup title in 2005, while Japan has only ever reached one final, and that resulted in a loss against the 32-time champion United States way back in 1921.
The Croatia-Japan winner will meet the Argentina-Germany victor in the quarterfinals in April.