Japan lock Justin Ives has declared himself fit for the Brave Blossoms' Rugby World Cup opener against South Africa on Saturday.

"Definitely, no doubt," Ives said on Monday night after Japan's second training session here, when asked if he could play if the Springboks game were tomorrow.

"It's feeling a lot better. It's close to 100 percent."

Ives injured the medial collateral ligament in his right knee on Aug. 15 when Japan lost to the World XV. The way he limped off the field late in the first half turned the clock back to four years ago, when he damaged his left knee ahead of Japan's first game against France in New Zealand and had to be sent home.

Ives acknowledges he had flashbacks when he went down last month.

"I still remember being in the room when JK (then-caoch John Kirwan) told the boys that I had to pull out because of an injury," the New Zealand native said.

"I still remember the tears and the support I've had since then from guys like Tomo (Luke Thompson) and Shota (Horie), and to have another go, to finally make it here is just unbelievable."

South Africa is the heavy favorites for the Pool B clash at Brighton Community Stadium but Ives, as well as the rest of Eddie Jones' squad, believes they do have a chink in their armor, small though it may be.

Jones helped the Springboks to the 2007 title as technical adviser and knows the team inside out.

"It's a unique opportunity to play these guys, one of the best teams in the world," Ives said. "We've been together for five months working really hard and I think we can ask enough questions to challenge them.

"They probably don't play rugby against people who play the way we play that often. If we can keep the ball in hand and just run and run the field, it's a great opportunity for us to create space."