With just one win in their opening three games, Rosenborg needed a result to keep their slim chances of progressing alive. 

Nicklas Bendtner put them ahead in the 55th minute, and the Norwegians were holding out for a huge three points. 

However, heartbreak struck in stoppage-time, with Zenit converting a 93rd minute equaliser to seal a 1-1 draw. 

Gersbach came on four minutes to go but could not help Rosenborg hold out for the win.

While it was a blow for Rosenborg, they still trail second-placed Real Sociedad by five points, with six points left up for grabs. 

Rosenborg take on Sociedad in Matchday 5, and anything other than a win means they will be knocked out. 

However, even if they do win, they need Zenit to beat Sociedad in the final Matchday, and Rosenborg must defeat Vardar.