The former goalkeeper claims the Super Eagles' last friendly will be key to showing if they are ready for Brazil as the squad welcomes back Africa Cup of Nations hero Sunday Mba
A late Uche Nwofor strike secured a 2-2 draw with Scotland on Wednesday as Stephen Keshi's men got their preparations for Brazil off to an unconvincing start.
However, 1996 Olympic gold medalist Dosu is confident that Nigeria will improve and has earmarked the meeting with Jurgen Klinsmann's side on June 7 as an important test ahead of the tournament opener against Iran.
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"With three matches to the World Cup, I think they will get their form back and the most important thing is that we did not lose," Dosu told Goal. "The basic thing is togetherness of the boys, playing together as a team. For me, the player that did very well is Joseph Yobo. He gave his best and he certainly has done well for himself.
"It will be too early for us to start celebrating our draw against Scotland but one thing is sure, it will give them the confidence to face the Greek side and I am very sure they will play better than they did today.
"The game against the United States of America will be the big one where we can now judge where we will get to at the World Cup. The team will step up their game in coming matches."
Meanwhile, Nigeria has been boosted by the return of Sunday Mba to the squad after the 25-year-old arrived late to the camp due to complications with his travel.
The CA Bastia midfielder, who scored the winner in the 2013 Africa Cup of Nations final, risked missing out on the World Cup due to problems with his visa as he tried to reach the training camp in America.
"His club wanted him in France and so he had to leave but we also made contact with the United Kingdom High Commission in France and they helped facilitate his quick arrival here," said Dayo Enebi Achor, the team's administrator.
"We must thank both commissions in Abuja and Paris for their help."