It was a monumental moment for Northern Ireland. Niall McGinn pounced on Andriy Pyatov palm out from Stuart Dallas' initial effort to slot home and seal the victory - his nation's first at a European Championships.
It came on the back of Sunday's anticlimatic defeat against Poland, a performance that was jittery, nervous, defensive and totally lacking in conviction. It was everything that the last two years under Michael O'Neill had eradicated and the pre-tournament euphoria produced only a damp squib.
Realistically, three points against Ukraine was essential if there was to be a serious case for progression further into the tournament from a hugely demanding group. New plans had to be drawn up to deal with the twin Ukrainian threats of Andriy Yarmolenko and Yehven Konoplyanka, but also to breach a stubborn defensive line.
O'Neill needed to make big calls and he responded by dropping five starters, including Kyle Lafferty.
Emphasis was placed on pace and vibrancy, the attacking trio of Conor Washington, Stuart Dallas and Jamie Ward constantly had the opposition on the back foot. Steve Davis, in his more natural central midfield position went back to controlling the tempo of the games, as he had done throughout qualification.
O'Neill setup a side who were defensively solid, more so than they had been against Poland - clearly more comfortable with the knowledge that they had an outlet from defensive positions and not continually facing wave after wave of attacking.
Post-match, O'Neill spoke of his extensive analysis of the Polish defeat and prioritised greater speed and penetration through the middle which was evident from the first whistle in Lyon as his side did not give their opponents a second to settle on the ball.
Unnerving teams, rattling them, providing a major set-piece threat, holding a lead and precise counter-attacks are exactly how Northern Ireland thrived in an excellent qualification campaign. O'Neill banished his doubts and returned to the shape and formation which he trusted.
Admitting errors in tactics and personnel is a sign of a world class manager - O'Neill showed that he is flexible, adaptable and proactive with his team selection and substitutions, all of which worked to a tee.
Not only did Northern Ireland prove that they have a great manager and an admirable team spirit, but they displayed their true class and ability. They showed that they belong on the biggest stage and who would now bet against them staying there?