Michael Flynn admitted Mansfield Town were too strong for his Newport County side.
Tyler Walker gave Stags a cracking start with a cool finish to give them a 12th minute lead.
And fellow debutant Otis Khan doubled that lead with a 56th minute header, before wrapping the game up on 65 minutes with a fine long-range effort.
Flynn was quick to admit that his side had been punished durin that period.
“I think the worst period was the 20-minute spell in the second half when they got their second goal,” said a frustrated Flynn.
“We lost the battle in that 20 minutes and they punished us. They scored two goals and really went for the jugular.
“It was frustrating because I thought in the first half, even though we were losing, we were playing quite well.
“But you can’t have 20-minute periods like we did in the second half where we were second best all over the pitch.
“Mansfield are a strong team and credit to them for finishing us off. They were stronger than us and you’ve got to give the opposition credit at times.”