Former Porto captain Bruno Alves has warned his Zenit St Petersburg team-mates to be wary of the threat posed by Hulk on Wednesday night.
Alves, who joined the Russian side from Porto in August 2010, misses the Champions League clash against his former club due to suspension, depriving him of the chance to come head to head with the burly Brazil striker.
But the 29-year-old is in no doubt as to Porto's dangerman at the Petrovski Stadion.
"Most of Porto's build-up goes through Hulk," he told the Russian press.
"He then usually comes into the centre to have a shot.
"Of course, Porto have other quality players, but most of their moves depend on one man. That is their strength and also their weakness."
Alves added: "The secret of Porto's success is their defensive solidity. But they are always looking for the best way to harness the talent of Hulk.
"Joao Moutinho is also very dangerous but then Zenit also have players, Danny and (Aleksandr) Kerzhakov for example, who can decide a game on their own.
"We are playing in our stadium and must win."
Zenit boss Luciano Spalletti acknowledged the importance of the game after his side were surprisingly beaten by group minnows APOEL Nicosia in Cyprus in their opening match.
"This is a pivotal match but we are ready," he said.
"We face a team recognised worldwide and that over the years has launched the careers of many important players and coaches.
"Although many have left Porto keep on winning. Only a strong attitude can ensure victory."
Porto have an unblemished record in Russia having won on each of their four previous visits.
A fifth would see them take control of Group G following their win over Shakhtar Donetsk last time out.
"This group's a four-way fight," Porto coach Vitor Pereira said. "It's a very strong group and it'll probably go down to the wire."
The visitors will be without midfielder Fredy Guarin through suspension but James Rodriguez and Alvaro Pereira return.