Watt beat Andrej Nedic 6-3, 7-6, taking the match in a tiebreak despite struggling physically.
“I felt like I let the crowd down yesterday,” Watt said in his on-court interview.
“I was cramping in that tiebreak, but I wanted to put my body on the line for my country.”
Then Shepp kept the Whangārei crowd cheering by taking the first set off Mirza Basic, 6-2. Shepp was up 5-2 in the second set but the 34-year-old Basic broke Shepp’s serve and then got back to 5-4 and had Shepp in trouble on his serve again at 15-40 before Shepp fought back.
He thumped successive aces to take the match and the tie and give New Zealand coach Artem Sitak one huge 40th birthday present.
The team rushed to embrace the 23-year-old Shepp, who told the crowd he was very proud of his teammates.
“We had a big task today [Sunday] coming back from two-zero. Credit to all the lads, we put on a really big performance,” he said on the Sky Sport broadcast.
“Honoured to be here. This is my debut so thank you very much for making me feel so welcome.”
New Zealand now progresses to the second round, which will be held after the US Open in September. The draw has not been done yet, so they don’t know yet who their opponents will be.
The next round will be in September, with the draw yet to be made.
If they win their second-round match, they make the final eight teams, plus the wildcard of Italy.