The former Chelsea central defender will lead Forest out this weekend.
Mancienne completed his switch to the City Ground over the summer, signing a three-year deal from German club Hamburg.
The former Chelsea central defender has been a virtual ever present in the Forest side who have performed so well this season, helping the club to an 11-game undefeated run at the start of the Championship season.
Despite going four games without a win, the Reds look well on their way to fight for promotion this season, and Stuart Pearce’s side will be looking to break their victory drought as they travel to Wales on Saturday to face Cardiff City.
Cardiff, who will be starting a game under new head coach Russell Slade for the first time since his appointment last week, have started the season less impressively, winning just three of eleven games, and dismissing former boss Ole Gunnar Solskjaer with the club sitting below mid-table.
Despite the differences in fortune between the two clubs, Mancienne told the official Forest website that it will still be a difficult game, with the Bluebirds looking to step up when they face the joint league leaders.
The 26-year-old said: “It’s definitely going to be a difficult game. They’re obviously not doing as well as they can do but everyone steps up their game against us.
“It’s going to be a real test. They’re going to give everything they can to impress the manager, better their position in the table and to take our unbeaten record away from us.”
The defender has impressed highly in his start at the City Ground, and he has been named club captain in the long-term absence of Chris Cohen, an opportunity that he plans to fulfil to the best of his abilities.
“I’m relishing it,” he added.
“It’s a big responsibility but I’m happy to take the captaincy and do the best I can for the club.
“Chris is a great captain and I want to do him, myself and the fans proud.”