World Cup super-sub Ritsu Doan believes the strength of Japan's bench could prove decisive as they prepare to face 2018 finalists Croatia in the last 16 on December 5 (10pm Cambodian time).

The Freiburg forward has played a crucial role as a substitute in Qatar, scoring the equaliser in Japan's shock wins over both Germany and Spain, which helped them top Group E.

Doan took four minutes to find the net after coming on against Germany and just two after entering as a half-time substitute against Spain.

He believes Japan's options on the bench can help them go even further as they seek to reach the World Cup quarter-finals for the first time.

"It's 11 against 11 but as players we talk about us playing with 26 against 11," he said on Saturday.

"The rules changed to allow five substitutes and I think we should be thankful for that. We have players who can change games."

Japan coach Hajime Moriyasu has won praise for his substitutions and tactical changes in Qatar.

Three of Japan's four goals at the World Cup have been scored by players who started on the bench, and substitute Kaoru Mitoma played the pass that set up the fourth.

Moriyasu has likened his men to baseball players, saying they all have roles to play including as "starters, relievers and closers".

Doan said he had learned how to make an impact coming off the bench from his club career in Germany and the Netherlands.

"I have scored a lot of goals after coming on as a sub," said the 24-year-old. "At PSV Eindhoven I started playing more as a sub and I know how to prepare to come on.

"Of course as a player I'm not happy about starting on the bench but as the manager says, we need to play with all 26 players at this tournament."

War of attrition

Doan was picked to start Japan's match against Costa Rica, which finished in a surprise 1-0 defeat.

He struggled to break down the Costa Ricans' stubborn defence and was replaced with around 25 minutes left to play.

Croatia will pose a different kind of test and Doan is prepared for a tough war of attrition.

"My impression of them is that they're a tough, dogged team," he said of Croatia, who lost to France in the World Cup final in Russia four years ago.

"They have a lot of veteran players and they have experience of how to handle a game.

"If you look at the last World Cup, they got through twice on penalties and once after extra time, so they all work hard and grind out the win."

Doan cautioned that Japan "haven't really been creating many big chances" so far at the World Cup and said Monday's game "doesn't need to be pretty".

Japan had just 17.7 per cent of possession against Spain – the lowest percentage of any team to win a World Cup game since records began in 1966.

Doan would become the first Japanese player to score three goals at a single World Cup if he nets against Croatia.

The forward said he is more concerned about helping Japan reach the last eight at a World Cup for the first time.

"I've been training from today trying to forget that I've already scored two goals," he said.

"The first thing is to get past the last 16."