Japan captain Makoto Hasebe Friday backed veteran striker Yoshito Okubo's surprise selection for the World Cup and said he could help inspire younger players.

Okubo has played only once in the last four years under Alberto Zaccheroni and there were audible gasps when his name was announced in the Italian's final 23-man group this week.

"Bringing him into the squad will increase the competition," Hasebe said of the Kawasaki Frontale forward, who was the J-League's leading scorer last season with 26 goals.

"But more than just that, he's also a 31-year-old veteran and I'd like him to help boost the atmosphere in the squad. He can be another leader."

Okubo started all four of Japan's games at the 2010 World Cup but he had not been considered a contender for Brazil, where they will aim to reach the quarter-finals for the first time.

Hasebe's place had also been in doubt after a knee injury in January which required two operations.

But he is confident of regaining full fitness after completing 90 minutes for relegated Nuremberg on the final day of the Bundesliga season last week.

"I've been injured so I've been in rehabilitation and all that goes with that," said the 30-year-old.

"I'm looking at it like it's pre-season training. In pre-season you get four to six weeks to get ready, and that's the way I'm thinking now."

Hasebe trained in 24 Celsius (75 Fahrenheit) heat outside Tokyo on Friday along with fellow Europe-based players Shinji Kagawa, Atsuto Uchida of Schalke and Southampton's Maya Yoshida.

"I think it's a little more humid here than in Brazil, and although the conditions will be different in different parts of the country, there will be places where it's like this," said Hasebe.

"Training in this kind of weather is very important. It's important to get used to it."

Japan qualified for the World Cup with ease and such is their confidence that AC Milan's Keisuke Honda even predicted they could shock the world and win the tournament.

Japan will first have to escape a tight first-round Group C featuring Colombia, Ivory Coast and Greece, but Hasebe said rallying his troops will be the least of his problems.

"The players in this squad all have a strong desire and I don't really have to do anything special as captain," he said.

"The players can all get themselves up for the games and there's no real need for me to bring everything together. I think that's what comes of this team being together for the past four years.

"I'm the captain but we have players like Eiji (Kawashima), Keisuke and (Yuto) Nagatomo who are all leaders. We have a lot of players like that, and I think the manager had that in mind when he picked the squad."