The ninth-placed Cowboys host the Sharks, in fifth, on Thursday night and must win to keep their NRL finals hopes alive.
Queensland forward Nanai missed the losses to Gold Coast and Brisbane after suffering a shoulder injury in the round-21 win over Parramatta.
His attacking threat on the edge gives the Cowboys strike and the 20-year-old has shown he likes the big occasion.
The Sharks clash is certainly a pivotal game in the Cowboys' season. They are on 28 points and outside the top eight on for and against, but have challenging clashes with the Dolphins and Penrith to finish the year.
Payten was just happy to have Nanai back after he missed a chunk of the season previously due to two suspensions.
"His period after his second suspension up until his injury he was really good for us and he had a strong impact on our team," Payten said.
"Jeremiah kept things really simple. He ran hard and tackled hard and built his game off that.
"He is an Origin player. He's played for Australia and he's only a kid. He is highly talented and gives everyone confidence when he is in the team.
"I am really excited to have him back."
Nanai's return allows Coen Hess to move back to prop and play in the middle of the park where he is most suited.
The Sharks walloped the Cowboys 44-6 in round nine and Payten said they posed real threats.
"They are a team that is fast and play with a fair bit of ball movement and you want to limit their opportunities in your half," he said.
"Teams that have stood up to them physically have tipped the result in their favour.
"The last game we played them they manhandled us physically and we were unable to stop it."
Payten said he didn't have to motivate his players with a semi-final spot on the line and the match also the 250th for club legend and co-captain Jason Taumalolo.
"Plus, we were embarrassed last time. So there is a number of things that should have our players ready to go," he said.
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