Nigeria's Ahmed Musa dazzled in the Volgograd heat as his second-half double secured a 2-0 victory over Iceland in Group D.
As temperature's reached 30 degrees in the Russian City, the pacey striker burnt holes in Iceland's back line, which began to crumble after half-time.
At the other end, it was Iceland's talisman, Gylfi Sigurdsson, who melted under the sun, missing a late penalty which would have set up a tense finish.
The Super Eagles grew in confidence as the match wore on and will now reach the knockout stages if they beat Argentina on Tuesday.
Francis Uzoho - 6
The 19-year-old keeper was not afraid to come off his line at set plays. Repelled some pressure by punching balls away.
William Troost-Ekong - 7
Assured at the heart of a three-man defence. Showed controlled aggression to win the ball in the air and on the deck.
Leon Balogun - 7
Dealt well with Iceland's aerial threat, winning numerous headers from long throws and crosses.
Kenneth Omeruo - 7.5
Solid at the back and his distribution improved as the match went on. His ball into the channel set up Musa's second goal.
Brian Idowu - 5.5
Saw out his defensive duties in the left wing-back role but struggled to get forward. Subbed off at half-time.