KL Rahul says India face a "very, very difficult decision" over who bats at number five in the first Test against South Africa at SuperSport Park.

Rahul, vice-captain in the absence of the injured Rohit Sharma, gave a strong indication that the tourists will persist with playing five bowlers in the Boxing Day Test behind closed doors in Centurion.

He said: "I think more teams have started playing [five bowlers], because, you know, every team wants to pick up 20 wickets, and that's the only way you can win a Test match.

"We've definitely used that tactic, and it's helped us in every Test match that we've played away from India. I think the workload also becomes slightly easier to manage with five bowlers, and when you have that kind of quality, you might as well use it."

We’ve had a great week of preparation.

Vice-captain @klrahul11 takes us through how #TeamIndia is getting into the groove for the first #SAvIND Test. pic.twitter.com/qGB8YcZZ57
— BCCI (@BCCI) December 24, 2021

That will leave Ajinkya Rahane, Shreyas Iyer, and Hanuma Vihari vying for the number five spot.

Rahul conceded India face a selection quandary as they consider who should get the nod.

He added: "It is a very, very difficult decision to make, obviously. Ajinkya has been a very important part of our Test team and has played very, very crucial knocks in his career.

"The last 15-18 months, if I can think back, his knock in Melbourne was really, really crucial; it helped us win a Test match. That partnership with [Cheteshwar] Pujara at Lord's in the second innings where he got a fifty was really important, and that ended up in us winning the Test match.

"So he's been a key player for us in the middle order, and he's a very, very strong player.

"Shreyas obviously has taken his chances. He played a brilliant knock in Kanpur [against New Zealand], got a hundred; so he's very exciting. And Hanuma has done the same for us, so yeah, it's a tough decision.

"But we'll start having a chat today or tomorrow, and you'll get to know [who gets the number five spot] in a couple of days' time."

India have never won a bilateral Test series in South Africa, with the Proteas coming out on top in six out of seven.

The tourists will also be looking for a first victory at SuperSport Park in the longest format, having lost both of their previous matches at the venue, but they have won four consecutive Tests against South Africa.