A goal by Karlen Mkrtchyan in the fourth minute of injury time steered Anzhi Makhachkala to the brink of qualification for the Europa League knockout stages as they claimed a priceless 1-0 victory at Tromso.
The game had appeared to be heading for a goalless draw when Mkrtchyan headed home for a deserved win for the Russians, who had dominated the first half before a limp display by both teams after the break.
Victory leaves Anzhi five points clear of FC Sheriff, who lost at Tottenham, with just two games remaining - while the Norwegians have just a solitary point.
Anzhi started the match with some urgency with Alexandru Epureanu, Mkrtchyan and Silva Jucilei all producing efforts without testing Tromso goalkeeper Marcus Sahlman.
Tromso were almost invisible and Anzhi's domination was almost rewarded after half an hour when Abdul Razak's left-footed shot was tipped round the post by Sahlman.
Another corner moments later ended with Epureanu firing wide and Alan Gatagov twice fired over, while the striker's weak effort was comfortably held by Sahlman as the game reached half-time goalless despite the visitors' domination.
There was little real action on the resumption with neither side really stringing together any meaningful moves.
It was not until the 62nd minute when Tromso had a real shot on goal, Runar Espejord firing wide as the game meandered along, before Steffen Nystrom also shot past the post for the hosts.
Anzhi had not been able to recreate their first-half urgency, substitute Odil Ahmedov shooting over the bar and Benoit Angbwa heading wide but time was against the Russians.
Ahmedov failed to threaten the goal with his injury-time effort and a stalemate beckoned before sub Serder Serderov's cross was helped on by Gia Grigalava before finding Mkrtchyan in the six-yard box - and he headed into the top right-hand corner of the goal.