Dinesh Karthik is picked for specific skill: Rahul Dravid

Veteran campaigner Karthik showed glimpses in his designated role at the end of an innings with a brilliant half-century (55 off 27) in Rajkot and two unbeaten knocks during the series that caught the eye of Dravid. He also became the oldest Indian batter to register a fifty in the shortest format.

"He (Karthik) is picked for a very specific skill and he was picked for that based on what he has been doing particularly well over the last two or three years," Dravid said after rain washed away India's chances of winning the five-game series against South Africa on Sunday.

"It almost came together perfectly for us in that game at Rajkot when we needed that big performance in the last five overs to be able to make a par score. He and Hardik (Pandya) batted beautifully for us and both of them are our enforcers at the end and guys that can capitalise on the last five or six overs as well as anyone in the world.

"It was really nice to see Karthik come off and do what he has been picked to do and it certainly opens up a lot more options for us going forward. Innings like that means he is certainly knocking very hard."

While the start of the ICC Men's T20 World Cup in Australia is still more than three months away, India still have many questions unanswered surrounding the make-up of their final 15-player squad for this year's tournament.

Squads for the T20 World Cup will need to be finalised by early October and Dravid said he is starting to form a picture in his mind about what he wants his touring party to look like.

"As you come closer to events you want to be able to finalise your final squad as quickly as possible. We can only take 15 to the World Cup, but you want to have your top 18 or 20 players (chosen)... and that you are clear on that and what type of squad you want to take to the World Cup," he said.

India still has at least 13 T20Is to play before they fly to Australia, with matches against Ireland (two), England (three), West Indies (five) and Australia (three) slated between now and the start of the tournament on October 16.

Dravid wants his fringe players to perform during those warm-up matches to ensure they make their case for selection unequivocal.

"I was telling the guys that they have to bang the door down. It is not about knocking on the door, they have to start banging the door down.

"We are going to start looking to finalise that squad as quickly as possible. Whether that will happen in the next series or the series after that is hard to tell, but we are certainly looking to do that as quickly as possible," Dravid said.