The European U21 championships got off to a bad start for hosts Denmark when they suffered a 1-0 opening defeat to Switzerland, though were left to rue a late refereeing decision and a fine performance from Swiss goalkeeper Yann Sommer.
Xherdan Shaqiri followed his fine display his senior team at Wembley last week with a 48th minute winner struck with his left foot.
The FC Basel prodigy had already fired in a few sighters and was the dominant force in a goalless first half before scoring just after the break.
The second half saw the home side, with Ajax's Christian Eriksen at the core, be the most threatening as Sommer made a series of fine saves from Andreas Bjellend and Nicki Bille Nielsen. The latter had the ball in the net in the dying minutes but was marginally offside - at best - when finally beating Sommer.
That result puts the host at the bottom of Group A after Belarus stormed to the top after something of a surprise win against Iceland in an earlier game which preceded the opening ceremony in Aalborg.
A drab game in Aarhus looked to be headed for a goalless final whistle before Iceland were shattered by two late Belarus goals and a sending off in a 2-0 defeat. Having missed three chances through Kolbeinn Sigthorsson, the much-vaunted AZ striker,
Iceland paid the penalty when Aron Gunnarsson was given a straight red card for a professional foul on Stanislav Dragun, from which Andrei Voronkov scored from the spot in the 77th minute.
Substitute Maksim Skavysh completed the win for Belarus with a well-taken chip over Iceland keeper Bjornsson and he and his team-mates celebrated wildly at the final whistle and now look to have a good chance of reaching the semi-finals, where the likes of England and Spain may lie in wait.