Debutant Laszlo Kleinheisler scored the only goal of the game as Hungary beat Norway 1-0 in Oslo to take a big step towards Euro 2016.
The 21-year-old starred on his senior international bow and netted with a dipping shot midway through an end-to-end first half.
Norway dominated possession after the break but their lack of a proven goalscorer - no one in the squad had more than three goals to their name - showed as they had no cutting edge.
Pal Helland hit the crossbar in the closing stages as the hosts' luck deserted them.
The play-off second leg in Budapest on Sunday will now determine who progresses to the tournament in France; with Per-Mathias Hogmo's men knowing anything less than an away victory will see them eliminated.
Norway flew out of the traps and Per Skjelbred's rising shot brought a fine save out of veteran goalkeeper Gabor Kiraly on his 100th cap, before Even Hovland had a great opportunity from the resulting corner but his header from Stefan Johansen's delivery was off target.
Hungary attempted to respond when Kleinheisler forced Orjan Nyland to repel his first-time effort having been set up by Krisztian Nemeth and that was a warning sign as the visitors went on to take the lead on 26 minutes.
Kleinheisler controlled a bouncing pass from Akos Elek and unleashed a quick left-footed effort which Nyland could not prevent from finding the far corner, despite getting a hand on the ball, sparking wild Hungarian celebrations.
Norway should have drawn level when a throughball from Skjelbred fed Alexander Soderlund, but the Rosenborg striker hit a tame effort straight at Kiraly.
Hungary threatened a second goal just before the break when Kleinheisler's cross found its way to Elek in the six-yard box, but the midfielder headed over.
Norway had most of the possession early in the second half but had Nyland to thank when he saved Balazs Dzsudzsak's effort from a tight angle after a weaving run in to the box on the counterattack.
Hogmo was furious on the touchline moments later when the Scandinavians were denied a penalty. Omar Elabdellaoui ran into the right-hand side of the area, but referee Mark Clattenburg disagreed with his claims that Tamas Kadar had tugged him back.
Elabdellaoui was booked for simulation midway through the half as he had another claim for a spot-kick turned down after colliding with Elek.
Attila Fiola had to desperately clear off his own goal-line after Kiraly had made a hash of dealing with a corner, but Norway struggled to create clear opportunities of their own as Martin Odegaard remained unused on the substitutes' bench.
The home side's best chance of the match came with only two minutes remaining when Johansen's shot was tipped into the air by Kiraly and Helland could only head against the bar from the rebound with an open goal gaping.