Iran came from behind to beat Japan in full sets on Friday to hand the host nation its third defeat at the FIVB Men's Volleyball World Cup, a qualifying competition for next year's Rio de Janeiro Olympics.
Japan won the first two sets but Iran left the home fans disappointed as its block, and Japan's errors, saw the match sway its way, winning 22-25, 23-25, 25-18, 25-21, 15-12 at Osaka Municipal Central Gymnasium.
Yuki Ishikawa and Shahram Mahmoudi were joint top scorers for Iran and Japan, respectively, with 20 points apiece.
Japan dropped to 5-3, while Iran, which also beat Japan at last year's Asian Games, has a 3-5 mark.
The unbeaten United States maintained the top spot on 24 points after beating Tunisia 3-0 for an eighth straight win.
Second-place Poland defeated Australia 3-0 to also make it eight wins from eight. Italy and Russia also both won and have 7-1 records.