Scores were level at halftime but New Zealand were made to pay for missed first-half opportunities and a disjointed second spell as Mexico netted all five goals after the break.
The policy of trialling players and combinations ahead of the World Cup continued with four changes made by the start of the second half and another shortly after when the score was still 1-0.
“We should have been up at halftime, we had enough chances,” said New Zealand coach John Herdman after the game.
“Mexico had one shot in the first half and a young player has missed a sitter for us at the other end.
“We’ve come in thinking we should have been two goals to the good but we weren’t. We made the changes we planned to and unfortunately some of those fresh players got exploited.
“The bottom line is that it was a poor performance in the second half.”
While Mexico might take a psychological boost from the victory Herdman his confident his opposite number will be none the wiser about how the Ferns will play when the two meet in their final FIFA Women’s World Cup group match in Sinsheim, Germany on July 5.
“We started with a completely different shape, something that the Mexicans will not take too much away from, and we haven’t shown our true hand at all. They’ve played a similar line-up throughout the tournament and today they’ve played key players in positions that we’ll see them in the World Cup.”
Canada won the 12-nation event with a 2-1 extra-time win over the Netherlands while New Zealand finished eighth.
Next up for the Ferns is a likely four-game tour of Australia and China in May and Herdman is signalling a change in approach after running the rule over players during the Cyprus Cup.
“We’ve got clarity now moving into the next phase of our preparation. We know which players will start games, which will close games for us and which will be used as impact players with something a little different,” he said.
“Those games in Australia and China will be about putting in winning performances with the right players on the pitch at the right time.”
Substitute Ria Percival became the youngest ever Football Fern – at 21 years and 94 days – to play 50 ‘A’ internationals, beating by 10 days a record set by teammate Abby Erceg last week. She is the eighth Football Fern to reach the milestone and the third to do so on the current tour following Erceg and goalkeeper Jenny Bindon.