Japan captain Minoru Ueda is upbeat about his team’s prospects for the second round of the Davis Cup Asia/Oceania Zone in April even though ace Kei Nishikori again could miss the competition.

After Japan wrapped up a 5-0 win over Indonesia on Sunday to set up a tie against either South Korea or India, Ueda said his team learned a lot about itself in the absence of Nishikori, the nation’s highest-ranked men’s player of all time.

Japan almost lost in the doubles a day earlier, but Indonesia did not pose much of a threat in singles, failing to win even a single set off the host country.

Ueda was particularly pleased to see Tatsuma Ito and Davis Cup debutant Yasutaka Uchiyama come from behind to win the doubles in five sets. The doubles has been a thorn in the side of Japan, which lost all four of last season’s doubles matches.

Ueda said his team’s ability to roar back without world No. 21 Nishikori — whose knee injury is not serious, according to the captain — shows the squad’s depth gives him more future options.

Japan has three players in the top 100 — Nishikori, Go Soeda (67) and Ito (84) — and can advance to the World Group playoffs in September if it gets past the second round.

“We fully expected ourselves to win the first round in Asia/Oceania,” Ueda said. “But you never know what can happen in tennis so I’m relieved we won.”

“We were worried about (Christopher Rungkat, Indonesia’s highest-ranked player at 252nd) because he can be tenacious. We really prepared for the match against Rungkat on the first day. But he’s played here before so we had him scouted; we knew what to expect from him.

“This was a good Davis Cup for us because we got a lot out of it. We can look forward to April with our players knowing what they need to work on.”

Ueda, Japan’s former Fed Cup captain who replaced Toshiro Sakai starting this season, believes the troops now know what to expect from him, and have come to understand what it means to play for the team.

“Playing tennis as an individual and as part of a team are two entirely different things,” Ueda said. “In a team competition, it’s important to be vocal, to pump your fist when good things happen because it gets your teammates going.

“Individually, the six players on the current squad all need to improve their rankings. Individual improvement will inevitably lead to the improvement of the team.”