A South Australian man is the lucky winner of last night’s $50 million Powerball jackpot.

What makes his win more incredible is that he said he was playing with his late mother-in-law’s numbers.

The man from Adelaide’s western suburbs said the numbers had special significance to his family.

He told SA Lotteries: “The numbers are actually those of my late mother-in-law, and we always knew that she would look after us.”

He was a registered player and lotteries officials were able to contact him just a few hours after the draw.

"I've won $50 million. What a head spin," he said.

"I’m absolutely speechless.”

He said he wasn’t yet sure how he was going to spend his winnings and was going to spend some time to comprehend his new found fortune.

The numbers were 2, 7, 17, 25, 28 with the Powerball 26.