Everton were dealt a late blow when Ari struck for FC Krasnodar in the 43rd minute of the first half of their Group H Europa League clash in Russia.
The warning signs for Everton came almost instantly when they were easily dispossessed in the first few minutes, which led to Mauricio Pereyra firing a shot from 25 yards, but it stroked over the bar.
Minutes later, Marat Izmailov got a chance to give the home side an early lead, but his shot from six yards out flew over the target after he was unable to get his footing right in time.
Krasnador continued to dominate the attack as Phil Jagielka was forced to block a volley taken by Odil Ahmedov, who was aiming for the back of the net.
Goalkeeper Tim Howard was called into action shortly afterwards and he was able to make a one-handed save to stop Marat Izmailov's shot from driving into the bottom corner.
Everton came into the game as the half went on, forcing two quick saves from Andriy Dykan, who was able to push away a 20-yard shot from Aiden McGeady and an effort from Gareth Barry, who attempted to curl the ball past the keeper.
Minutes later, McGeady was able to find the head of John Stones with a cross into the box, but the defender's header went wide of the target.
Despite a spell of attacking energy from the Merseyside outfit, Krasnodar began to control possession once again by pressing their opponents back into their own 18-yard box.
The home side created some nervy moments for Roberto Martinez's side, and their attacking threat eventually paid off in the closing stages of the half when Ari volleyed the ball into the corner of the net after both Phil Jagielka and Stones failed to clear the danger.