Mustafizur Rahman's eyes sparkled when asked, for the fourth time, how he felt after taking three wickets in four balls in the first innings of his debut Test. His spell of 4 for 37 had broken South Africa and the visitors had fallen for 248 in Chittagong.

"Do I even have to tell you? Three wickets!" he said, with a clap and a big smile. That is also how he celebrates his wickets. Some have compared it to a happy baby, and there was even a mention of him resembling a flapping seal.

It was hard to get a proper word out of Mustafizur. Out in the middle at the Zahur Ahmed Chowdhury Stadium, he had been in his element, but in front of cameras and reporters in an air-conditioned room he was not at ease. But he tried.

After Bangladesh's poor start in the first session, Mustafizur said the idea had been to string dot balls together and form a bowling partnership that squeezed the South African batsmen. "In ODIs, you sometimes just have to keep the ball in certain areas. Batsmen try to go after the bowlers and end up giving away wickets," Mustafizur said. "It is not easy to take wickets in Tests. Batsmen leave good balls alone. You have to earn your wicket in Tests.

"I wasn't bowling well in the first spell. I kept trying to take wickets and build a partnership together with the bowler at the other end. I was trying to bowl dot balls, even if I wasn't taking wickets. We knew that if we could put pressure from both sides, wickets would come."

Mustafizur said he deliberately varied the usage of his offcutter, a delivery that had brought him most of his wickets in the ODI format. "I think I try the variation twice or thrice per over in an ODI. I was trying them once every two or three overs. Batsmen are not in a hurry to score runs in Tests so I didn't try it much."

He said he was particularly pleased to claim Hashim Amla as his first Test wicket - to go with Shahid Afridi in T20Is and Rohit Sharma in ODIs. "Hashim Amla's wicket gave me most pleasure," Mustafizur said. "I am thrilled to have taken the wicket of a batsman of such caliber. I tried to take the hat-trick. I bowled exactly what I wanted to bowl, but the batsman played it well and I didn't get the wicket. I was happy when I saw the stump flying. I am supposed to feel that way.

"It is great to take wickets like this. There is no fun in fielding for two days," he said when asked how much effort he put in on a slow pitch.

Despite taking four wickets, Mustafizur enjoyed his signature celebration of clapping only once - when he dismissed Quinton de Kock with an inswinger, his third wicket four balls. He then tried to make eye contact with the batsman.

The story is in Mustafizur's eyes. It tells the tale of a 19-year old boy from a village living his big dream.