The Iranian team defeated FIVB World League title-holder in straight sets (25-19, 29-27, 25-20) in Pool B of the FIVB World League.
Shahram Mahmoudi scored 17 points to lead Iran to the convincing victory over unbeaten USA. The win opens the door for Poland to move level on points with the USA in Pool B, whilst Iran will go into the remaining fixtures with hope of taking second place.
Matthew Anderson and Aaron Russell got 12 points each for USA.
USA and Iran first met in 2015 the first weekend of World League on May 30-31. USA won both matches, 3-1 at the Galen Center in Los Angeles before large crowds that included many Iranian fans.
Poland also beat struggling Russia 3-1 (30-32, 25-14, 25-22, 25-18) in Kazan.
USA leads Pool B with 17 points, Poland is second with 14 points and Iran remains third, bagging 10 points. Russia has a single point.
