Defender Atsuto Uchida spared Japan's blushes with a 43rd-minute winner as the Asian champions beat Cyprus 1-0 in their final home World Cup warm-up game on Tuesday.
Japan, who looked heavy-legged after a punishing training camp last week, face Ivory Coast in their opening game at the World Cup in Brazil on 14 June. Right-back Uchida broke the deadlock in Saitama when he stabbed home the loose ball after Shinji Kagawa's close-range effort had been blocked, registering only his second goal in 66 internationals.
"It was nice to score coming back from injury," said Uchida, who celebrated his strike by sprinting to the touchline to hug the Japan coach, Alberto Zaccheroni.
"I didn't know if I would be fit in time," added Uchida, returning from a lengthy spell out with a thigh problem. "I really wanted to get on the scoresheet tonight."
"I'm not the sort of person to make promises about results."
With Cyprus defending resolutely, a clever step-over from Kagawa brought the crowd of 58,000 to their feet, only for Keisuke Honda to waste Japan's only other chance of a scrappy first half. Kagawa and captain Makoto Hasebe, himself working his way back to fitness after a knee problem, went close as Japan showed more urgency after the break.
Ultimately, the home side lacked the cutting edge that Zaccheroni had demanded before the match. "We weren't as sharp as we can be but the players kept probing," said the Italian, who has stubbornly refused to make any World Cup predictions.
"I'm not the sort of person to make promises about results. But I do demand the players put in the effort required to get results. We will be 100 per cent on 14 June."
Japan, who also play Greece and Colombia in Group C, have further friendlies against Costa Rica on 2 June and Zambia on 6 June in Tampa before flying to Brazil. Japan stormed through Asian qualifying to secure a fifth successive World Cup appearance, finishing four points clear of Australia at the top of their final-round group.