Kagawa, despite early success at Old Trafford, admitted he was below par in last month's 1-1 friendly draw with Venezuela, when he gave the ball away for the visitors' equaliser and missed several goalscoring chances.
"The final round of qualifiers has come back around and I have to pull my socks up," he told Japanese media, ahead of Thursday's friendly with United Arab Emirates. "I didn't play too well in last month's game and this is an important match."
The former Borussia Dortmund man will play on the left of the attack against UAE when Japan take on Iraq in Saitama next Tuesday. His preferred position, a central role behind the striker, is filled by CSKA Moscow livewire Keisuke Honda.
Kagawa conceded he was unlikely to shift Honda, coach Alberto Zaccheroni's automatic choice in the position who has scored four times already in the last round of qualifying for Brazil 2014.
"Obviously I always want to play in the hole but no matter what I say the situation isn't going to change," Kagawa said. "That's the way it goes and basically I just have to deliver results in whichever position I am played in."
Zaccheroni said he hoped the move to Manchester United would do Kagawa good.
"When the club is doing well, he is playing well and I hope he also plays well for the national team," he said,