Ireland were in with a big chance for a maiden ODI win over New Zealand, courtesy of a cracking first international century by lefthander Niall O'Brien.
However man of the match Santner was brought back by captain Tom Latham when the heat was on and he responded impressively, taking four for seven in his four-over spell to finish with five for 50, his best ODI figures.
New Zealand, sent in, owed a debt to Neil Broom, whose racy 79 off just 63 balls, put some punch into the innings. They reached 289 for five on a slow-paced pitch.
Opener Luke Ronchi got to 37 in a hurry while Ross Taylor made 52 off 60 balls, sharing an 84-run stand in 20 overs with lefthander George Worker.
Worker found it hard to get moving on the holding pitch, his first 27 runs taking 61 balls.
His dismissal had New Zealand 194 for four with 11 overs left but Broom and Jimmy Neesham banged on 79 in 9.1 overs and New Zealand would have felt they were well positioned at the halfway mark.
The Irish seamers struggled for a tight line early on, although there were tidy performances with the ball from seamer Kevin O'Brien and left arm spinner George Dockrell.
Scott Kuggeleijn, on debut, had a brace of wickets in consecutive balls to set Ireland's chase back early. However a third-wicket stand of 86 between O'Brien and Andy Balbirnie got the Irish into the contest.
They could sniff a famous win as O'Brien and Gary Wilson trimmed the target significantly and had Ireland well ahead on comparative run rates with their 75-run stand in 11 overs.
The fourth 50 of the innings took only 37 balls as Santner and seamer Neesham took some punishment.
O'Brien, a veteran of English county cricket with Northamptonshire and Leicestershire, produced outstanding footwork in his classy innings.
He drove strongly through the offside, thumped debutant seamer Seth Rance over long off for six and went to his hundred lifting legspinner Ish Sodhi for another six over long on.
However Ireland needed to give O'Brien support if they were to enjoy a spot of history.
Instead they dropped into a hole, losing three quick wickets.
Wilson went softly, pushing Kuggeleijn to Taylor at short cover; Santner had debutant Simi Singh easily stumped; and Dockrell was splendidly caught, diving one handed to his right by captain Tom Latham, the Irish were wobbling.
While O'Brien survived Ireland were still in business.
He was badly dropped by Worker at long on off Rance on 107 as New Zealand became rattled in the field late on.
However he was stumped off Santner and the end came quickly.
Rance got the final wicket, his first in international cricket. Kuggeleijn finished with three for 41 but it was a solid workout for New Zealand, who became rattled late on in the field.
New Zealand will play Bangladesh starting late on Wednesday night at in their second match of a series which is preparation for the Champions Trophy in England next month.
