SYDNEY - A New Zealand man who won NZ$19.1 million (S$17.68 million) in the Powerball lottery last month was told to go home after he showed up for work on a major motorway project after the win.

"He turned up for the work, and I think the rest of the team said, 'Mate, you probably need to go home,'" one of his co-workers told current affairs TV programme Seven Sharp.

"We were fortunate to have one of our people on the project, and whammo, he won the winning ticket," he added.

The man shared the NZ$38 million jackpot with a Wairarapa family syndicate, reported The Sydney Morning Herald.

He checked the ticket when he went to get some groceries from his local supermarket on Monday night. "I handed over my ticket to the lady behind the counter and the words 'Congratulations, you are a first division winner' flashed up on the screen," he said.

"I asked the lady, 'What does this mean?' But the expression on her face gave it away - her eyes were wide and she had a massive grin on her face," he said.

"I'm the type of guy who likes to contain my emotions, so she probably thought I wasn't even excited. If only she knew how I was feeling inside; I was bursting with happiness," he added.

After the good news, he went for a swim in the ocean to calm himself down before returning home to tell his partner about the big win.

"While I was swimming I had been thinking about how I wanted to tell her, so I wandered in the house and causally asked her, 'Did you hear someone in Warkworth has won $NZ19 million?'," he said.

"When she turned to look at me I said 'and you're looking at him'. She just stared at me in shock, trying to read my face," he said. "When she realised I wasn't joking, we had a big hug and a kiss - it was a very special moment."

The man is now taking some time to figure out his next move. "I feel very fortunate to have won, but I want to let everything settle down a bit before I make any big decisions," he said.

However, it appears unlikely that he will return as one of the 500 workers putting the final touches on the 18.5km Puhoi-Warkworth motorway that is due for completion by the end of 2021.