Guptill was one of the stand-out players for New Zealand in their ICC Men's Cricket World Cup 2015 campaign, when they were runners-up, finishing with 547 runs, including a World Cup-record 237 against West Indies. This edition, however, he has made just 167 runs in nine innings so far, averaging just 20.87. With their openers not clicking, New Zealand's middle order has come under pressure.
Guptill, who has come in for criticism for his poor run of form, admitted that it had hurt his confidence. "It's bloody tough," he told 1 News in an interview. "You try not to read what people are writing and hear what people are saying but it's hard to tear away from it all.
"The hard work goes unseen," he added. "I've put a lot of time in and for it not to be working out in the middle it's frustrating. People can say they're frustrated with me but no one is more frustrated than I am."
The opener has 976 runs in all 50-over World Cups, and could soon join Stephen Fleming in the list of New Zealanders who have 1000 runs in the tournament. He insisted that he was feeling better than ever at practice, and backed himself to do well.
"Even in the nets, I feel like I've been found wanting a bit. [But] the last couple of nets I've probably felt the best I have since I've been here ... It's starting to feel like it's coming back together. Which is promising!"
Explaining why things weren't clicking, he added, "I've felt a little bit late on the ball in quite a few games, which is hard to deal with. You don't want to move too early because then you get stuck.
"I'm just trying to carry on with what I've been doing, work hard in the nets and hopefully in the next game it all comes together."