Nigeria and Iran have been forced to settle for a point each in their Group F opener following a goalless draw in Curitiba.
It was a bright start from Nigeria as Victor Moses unleashed the first shot from outside the box in just the third minute to test Alireza Haghighi.
Nigeria continued to dominate the early stages, with Emmanuel Emenike a threat in the build-up to a great chance for Ogenyi Onazi, who fired wide after finding space inside the box.
Despite sitting back and soaking up the pressure for most of the first half, it was Iran who created the best opportunity just after the half-hour mark when Reza Ghoochannejhad lost his marker to force Vincent Enyeama to push a header to safety.
Nigeria continued to be frustrated going forward either side of the break, with Iran's stubborn defence making it difficult for the African champions to find the space they needed in attacking areas.
Ghoochannejad looked lively when he managed to get involved further up the pitch, but he failed to trouble Enyeama for a second time when curling a speculative effort wide of the target.
Shola Ameobi was introduced to add another option in attack for Nigeria, and he almost made an impact with a clever pass to Emenike, who could only fire a poor effort over the crossbar.
A venture forward from the Iranian almost produced a goal in the 78th minute when a deep cross found Ashkan Dejagah at the back post, but the Fulham attacking midfielder mistimed his jump and could only direct a header wide.
Ameobi's presence in the box caused problems late on, with Mehdrad Pooladi twice being forced to make vital clearances as Iran secured the draw.