After carrying his bat for 117 in the first match which New Zealand won by eight wickets, Guptill made 118.
Opener Martin Guptill made a second consecutive century to guide New Zealand to an eight-wicket win over Bangladesh in the second one-day cricket international on Saturday and a 2-0 win in the three-match series.
After carrying his bat for 117 in the first match which New Zealand won by eight wickets, Guptill made 118 as New Zealand — at 229-2 — surpassed Bangladesh's total of 226 with almost 14 overs remaining.
Guptill's century on Saturday was the 16th of his career and his third of the summer after his 138 in the first one-day international against Sri Lanka in early January.
Bangladesh was coming off an impressive series victory in the West Indies. But a single warm-up match sent them into the ODI series under-prepared and they have struggled to adapt to New Zealand conditions.
Sent in to bat after losing the toss on Saturday, Bangladesh's top order struggled on a pitch at Hagley Oval which contained moisture under a tight-packed covering of grass. The ball seamed a little and the Bangladesh batsmen struggled to cope.
Bangladesh captain Mashrafe Mortaza hoped his batsmen could survive the threat of the new ball, then hit out later in their innings and set New Zealand a challenging total.
While Bangladesh was reduced to 5-93 in the 21st over after a slow beginning, it began to hit out strongly in the second half of its innings.
Mohammed Mithun, who top-scored with 57, put on 75 for the sixth wicket with Sabbir Rahman (43) and at 168-5 in the 35th over, Bangladesh was in a good position to launch. But the lower order faltered and the last five wickets added only 58 runs, with the last wicket falling with two balls to spare.
When New Zealand batted, Guptill and Henry Nicholls quickly asserted the host's dominance, taking 23 runs from the first three overs.
Nicholls fell with the total 45 but when Guptill was out for 118 in the 29th over, New Zealand was 188-2 and coasting to victory.
Kane Williamson completed his 37th one-day international half-century and was 65 not out at the end, hitting a boundary for the winning runs, while Ross Taylor was 21 not out. He put on 143 for the second wicket with Guptill to put the win beyond doubt.
"Another clinical performance for us is what we're wanting," Williamson said. "I thought the lads in the first half with the ball in hand were outstanding."
