Former Porto favourite Hulk has vowed to show no mercy to his former club as Zenit St Petersburg look to take a big step towards qualification for the knockout stages of the UEFA Champions League on Wednesday.
Victory for Zenit over their Group G rivals in Russia would lift them four points clear of Porto in second place and make them heavy favourites to progress along with group leaders Atletico Madrid.
And the Brazilian striker, who scored 54 goals in 99 league games for Porto between 2008 and 2012, says securing such a crucial advantage for his new club is the only thing on his mind.
Hulk told a press conference: "I grew up in Porto and won titles there so for me these are extra special games. But this will be a decisive match for Zenit and that is what makes it extra special.
"We were very unhappy with our last match in the Russian League. We could have won but we only got a draw - so we will play to win, even though a draw can be a convenient result for us."
Zenit have stumbled slightly since their superb 1-0 win in the reverse fixture in Porto last month, dumped out of the Russian Cup by lower-league Tyumen before drawing their home league clash with Amkar Perm on Saturday.
Coach Luciano Spalletti said: "I heard that Porto say they are coming here only to win and I think we have to think in the same direction.
"We all understand the upcoming game is one of the most important of the season for us."
Zenit have received a boost on the eve of the game with the news that Axel Witsel will be able to line up against Porto after having an additional suspension for his red card in an earlier group game against FK Austria scrubbed by a UEFA appeal committee.
Porto boss Paulo Fonseca saw his own side suffer a lapse in form at the weekend when they could only draw 1-1 at Belenenses, a result which cut their lead at the top of the Portuguese Primeira Liga to three points.
Fonseca has recalled midfielders Mikel and Diego Reyes to his squad which is set to take place in freezing temperatures in the Russian city.
Hector Herrera is banned after his red card against Zenit last month.