Haseeb Hameed will make his Test debut for England against India in Rajkot on Wednesday after Alastair Cook confirmed the Lancashire opener has replaced Gary Ballance in the batting lineup.

Cook, announcing the reshuffle on the eve of the first Test, also sought to clarify comments given in a recent interview regarding his future as captain, insisting it is “business as usual” and that, as has been the case since he was sacked from the one-day role in late 2014, he continues to weigh up his position on a series-by-series basis.

Of greater relevance to Cook before a five-Test encounter with India in which the home side begin as strong favourites, is the decision to install a new opening partner in Hameed, who will become the 10th batsman to assume the position since Andrew Strauss retired in 2012.

At 19 years and 297 days of age, Hameed will also be England’s fifth youngest Test cricketer and the youngest since Ben Hollioake against Australia at Trent Bridge in 1997, with his first cap coming on the back of an impressive county season in which he scored 1,198 first-class runs.

The right-hander’s inclusion means Northamptonshire’s Ben Duckett, who opened with Cook in Bangladesh, will move down to No4 with Jos Buttler of Lancashire, the other spare batsman in the squad, forced to wait his turn alongside Yorkshire’s Ballance, who averaged 19.9 in six Tests since his recall last summer.

Cook, who stopped short of naming his full side as he and the head coach, Trevor Bayliss, ponder conditions and the make-up of their bowling attack, said: “I can’t give my team as we haven’t trained yet and seen the wicket but I can tell you Has will open the batting and Ben will bat at No4.

“It’s an unfortunate decision on Gary. In his six Tests back he hasn’t quite scored the runs he would have liked. It’s given someone else an opportunity and it’s a very exciting day for a young guy who has impressed everyone so far on this trip.

“You wonder about picking a guy at 19, whether he might be overawed, but hasn’t been at all. He’s looked good in the nets.” He added, jokingly, “He has shirked 12th man duties which shows his experience at 19 and it’s very special day to pick someone so young.”

“He was picked on the tour and talking to Ashley Giles [Lancashire’s head coach] and the selectors, people who are very good judges of a player, it’s maybe a year earlier than he would have thought but it’s the way he has developed so quickly. He’s one of those natural run scorers. He should be very proud and hopefully do well.”

On Duckett moving down the order, after making his debut in Bangladesh and registering one half-century in his fourth innings, Cook said: “It’s not ideal to have two games at the top and change but he’s a pretty unflappable character.

“He had three tough innings then a really good one. Historically he has been a middle order batsman – it’s only in the last year he’s been at the top of the order – and he’s comfortable there. It’s never ideal when you chop and change.”

Cook, like Hameed, made his Test debut for England in India, doing so in Nagpur in 2006 aged 21 years and 67 days. The 31-year-old Essex batsman has since gone on to make 10,688 Test runs but believes his new opening partner to have greater ability than he possessed at the same age.

“He’s incredibly unflappable,” said Cook. “He looks a very good player of spin – he picks length very well and uses the crease well, both forward and back. Stuart Broad bowled at him last summer and was almost straight on the phone to me saying how impressed he was with this guy. A lot of people have said he looks like he can handle it.

“To average 50 in Division One as a 19-year-old is an incredible feat. I remember how hard it was and I was nowhere near the player he was at 19. It’s really exciting. Of course there are going to be some tough moments for him over the next few years of playing Test cricket, but this guy can play.”

Cook’s pre-match press conference on Tuesday included a number of questions regarding his future as captain, after he was quoted in the Cricketer magazine saying: “Deep down I don’t know how much longer I am going to carry on. It could be two months, it could be a year.”

The left-hander has previously stated he fancies a spell back in the ranks under new leadership before he retires from Test cricket – Joe Root, the vice-captain, is his heir presumptive – but despite this long-term plan, thoughts of calling time on his captaincy appear far from his thoughts at present.

Cook, who will this week surpass Mike Atherton’s record of 54 Tests as England captain, said: “It was just an honest answer to a question that is quite hard to answer. Someone asks: ‘How long do you go on for?’ Ever since the Sri Lanka series before the 2015 World Cup [when Cook was sacked as one-day captain] I have been open and said we’ll take it series by series.

“I said it could be two months – the end of the current series – six months, two years. I don’t know. The headline’s been made but my situation hasn’t changed. No one is talking about it in the dressing room. So to me, it’s business as usual. It’s a mountain out of a molehill.”