Belgian title holders Gent are a win away from the Champions League knockout round as they prepare to host Zenit.
Gent have been Group H's surprise package after taking seven points from their five fixtures to occupy second position heading into Wednesday's fixture.
But with Valencia - only a point adrift - hosting already-eliminated Lyon on the final matchday, there is no room for a slip-up.
Gent are assured of place in the Europa League at the very least and victory over Zenit would send the Belgians through, while they would also qualify if Valencia fail to beat Lyon.
Andre Villas-Boas' Zenit have been among the most impressive teams in the Champions League so far, winning all five of their matches to ensure they will finish as Group H winners.
Zenit will equal Spartak Moscow's Russian record of winning all their group matches and go into the trip to Belgium as strong favourites.
But former Chelsea manager Villas-Boas admits there are some "strange emotions" and "negative feelings" in his squad as the defending Russian champions are in fifth place, seven points from the top of the league following two matches without a win.
"The Champions League is different. We feel very positive, it's a historical record for us, trying to equal Spartak's six wins, and we feel positive emotions in the Champions League," he said.
"We try to motivate the players the same, Certainly, more in the Russian championship because in the Champions League we have no such problems.
"We started the season on June 20 and the team are a little tired. We are a small team, when we have injuries or suspension we suffer as we have a small squad."
Villas-Boas will be without suspended midfielder Axel Witsel for the sold-out Gent match, while Belgium international defender Nicolas Lombaerts returns to the club he played for between 2004 and 2007.
Gent have fitness doubts over Lasse Nielsen and Danijel Milicevic.
Gent coach Hein Vanhaezebrouck was relieved after his side squeezed past Zulte Waregem and qualified for the quarter-finals of the Belgian Cup in their last fixture.
"Everyone was too preoccupied with themselves," he said.
"It did not work and then was there someone else pointed instead of continuing work on the field. That cannot be," he said following the 2-2 draw, which brought an end to a four-match winning streak.
"If it does not fails then you have to fight for your team. I'm disappointed that I did not see that."
