Karthik had found himself out of favour as the selectors dropped him for India's final five ODIs before the World Cup.
"I think in the past two years he has showed us how versatile he is. He is not only a finisher but even batting up the order. I think he gives you that versatility also being a wicketkeeper and a very good fielder," Nayar said of Karthik.
It is well known that Nayar has put his 'friend' Karthik through a rigorous training program, leading to a turnaround that was reflected in the last-ball six during the Nidahas Trophy final.
"He is not only a keeper backup but also a batsman backup who can come and field. We've seen how well he fields and the kind of catches he has taken. He is also ideal to bat at number four because of the kind batsman he's you can use him anywhere in the batting order. So for me he is someone I feel he should be definitely in that World Cup squad."
KKR lost their last round match against Chennai Super Kings after being restricted to 108 for nine.
"I think one game doesn't define this team. Even in the last game, we fought till the end defending a small total and showed character overall," Nayar said, hoping for a turnaround against Delhi Capitals.
In their return leg clash, the spotlight is on Cricket Association of Bengal president Sourav Ganguly, who will be sitting in the opponents' dug-out as their advisor.
"We are fine as long as he's not playing. Having someone like Sourav is a great USP, but it's about the cricketers on that particular day that showcases their skill that wins the game," Nayar said without reading much into the scenario.
First Published: April 11, 2019, 10:05 PM IST