But don't let that fool you - Guptill is still one of the our best ever ODI batsman.
His century last night made him just the 5th Kiwi to score an ODI century on Australian soil. In fact, his 114 is the third highest total - just two runs shy of No. 1 Stephen Fleming (116).
Guptill also moves into third overall for ODI centuries with 11. Only Nathan Astle (16) and Ross Taylor (15) have more.
However, Astle batted out 223 innings, Taylor is on 176 and Guptill has just 132.
During the night, Guptill also became the 5th New Zealander to reach 5000 ODI runs, doing it in the shortest amount of innings.
He's currently 1000 runs behind Kiwi legend Brendan McCullum, though McCullum has 125 more innings under his belt.
And let's not forget Guptill still holds the record for the highest ODI score (237), with the next best being Lou Vincent, 61 runs away with 172.
Consistency is the biggest challenge for Guptill, as it can be for most openers.
But if he continues this form, and is able to hold his average of 42.95, there's no doubt he'll be knocking on the door of the No. 1 spot in each stat category - though he has a young and ambitious Kane Williamson chomping at his heels, and a still-handy Ross Taylor competing alongside him.
Hypothetically speaking, if he can get another ton during the series, he'll join an exclusive club with the likes of Brian Lara, Sir Viv Richards, and Virat Kohli - some of the only players to score more than one ODI century in Australia.