"It is still difficult to believe. To be honest, my expectations were just to get a contract. Never did I think something like this would happen," Duminy told reporters.
The elegant left-hander was bought for a whopping $950,000 at the IPL auction by Mumbai Indians, more than thrice his reserve price of $300,000.
Duminy, who played a stellar role in South Africa's recent series win in Australia, said the challenge would now be to perform under pressure, something he is used to.
"The pressure is going to be there but I back myself to perform under pressure. I was under lot of pressure to perform in Australia, especially in the one-day series. I wanted to show what I could do at this level," he said.
Duminy made a mark on his Test debut in December against Australia, hitting an unbeaten half-century in South Africa's record win in Perth.
The 24-year-old left-hander followed that up with a 166 in Melbourne to give his team the series. He averaged 58.33 in South Africa's 4-1 ODI series win.