Marshall is joining Guinness Premiership side Leeds Tykes this summer, leaving the way clear for the Chiefs star after dominating the All Blacks scene for more than a decade.
Marshall made his All Blacks debut in 1995 against France and has since gone on to win 80 caps for his country.
Kelleher may be a veteran of two World Cup campaigns but he has managed to claim only 35 caps since his bow in 1999 against Samoa in Albany, Auckland.
Kelleher, who started the second Test against the Lions after coming on in the first as a replacement for Marshall in Christchurch, has once again got the nod for the final match at Eden Park, Auckland.
However, he knows it will be an emotional night as coach Graham Henry has publicly stated Marshall will finish the match.
"It is sad," Kelleher said. "We've had a great rivalry, it's kept me honest and I've kept him honest.
"New Zealand rugby's going to be poorer for Justin going, but that's the rotation of players, that's professionalism. It is a sad moment but it creates opportunities for other people."
Kelleher has earned 21 of his 35 Test caps of the bench but he is now determined to hold down a permanent position behind the All Blacks pack as Henry's side begin to prepare for the World Cup in two years' time.
"The coaches have backed me on filling this position," he said. "It's nice that I've been able to put the pressure on.
"They've chosen me to fulfil their requirements and I just thrive on that opportunity. The hype's there for this game with Justin going.
The All Blacks have been rocked by a number of injury setbacks leading in to the final Test but Kelleher is confident the players brought in can complete a 3-0 series win.
"This will just show the depth that we've got, we back the skill and ability of the guys that have come in to fill the positions," he said.
Kelleher will be offering debut fly-half Luke McAlister a guiding hand behind the scrum but he is confident the rookie will not let anyone down.
"I'll just tell him what the requirements are and make sure he keeps talking to me," Kelleher said. "It's a challenge to make sure that link is still operating smoothly."
McAlister is no stranger to Kelleher as he trained with him on the All Blacks tour of Wales and France last year.
However, due to a niggling hamstring injury the youngster was the only player among the 32 tourists who did not get any game time on tour.
"He'll settle into the game nice and early," he said. "He's a great player and I'll get the ball to him as quick as possible. With plenty of experience around him I'm sure he will be okay."