But while he is in the No 3 spot, the Black Caps left-hander is keen to make the most of it.
The 30-year-old played the role of co-star during New Zealand’s monster 113-run win against Sri Lanka in Hamilton midweek.
He scored 62 from 52 balls and combined in a 112-run stand with Rachin Ravindra to help set up victory.
The win saw the Black Caps clinch the series, but they can secure a 3-0 sweep with a win in Auckland today.
And Chapman, who has batted everywhere in the order from No3 to No8, is enjoying an opportunity to bat at No3 in the series.
"Yeah, I'm pretty happy with how things are going in my game, personally," he said.
"I feel like I've sort of matured a little bit as a batter and, you know, as you've alluded to, I've been used in a few different roles in the order."
No 3 is where Williamson bats.
The selectors will name the squad for the Champions Trophy in Auckland tomorrow and several keys players, such as Williamson, are expected to be back in the mix.
If Chapman makes the squad, he will almost certainly be asked to bat a lot further down the order. Behind Williamson. Behind Daryl Mitchell. Behind Tom Latham. Behind Glenn Phillips. The best case scenario might see him bat at No 7.
"Oh, to be honest, I'm just really happy with the game time. Obviously Kane is probably our best ever player in history, so if you're dropping out for him, [then] you're sort of letting someone in that's pretty handy.
"So, yeah, I mean, you try not to think about it too much.
"You sort of look at the challenge that you've got in the here and the now and you just do your best in this moment.
"I think I've kind of been used in a number of different roles, so I guess that's one of the reasons they sort of had me in a few squads because I can bat in different positions.
"I pride myself on being able to adapt to the different batting positions and, yeah, just trying to put my best foot forward every time I go out there."
While the Black Caps have had Sri Lanka on toast during the series, Chapman said there was no room for complacency.
"We dropped the last T20 against the Sri Lankans. They put out a pretty amazing performance, but hopefully we can take the sweep here."
Chapman got his start in international cricket for Hong Kong. He played two ODIs for them before committing to making the Black Caps.
Third ODI
Auckland, 2pm
Black Caps: Mitchell Santner (captain), Tom Latham, Will Young, Rachin Ravindra, Mark Chapman, Darryl Mitchell, Glenn Phillips, Mitch Hay, Nathan Smith, Matt Henry, Jacob Duffy, Will O’Rourke, Michael Bracewell.
Sri Lanka: Charith Asalanka (captain), Asitha Fernando, Nishan Madushka, Nuwanidu Fernando, Avishka Fernando, Wanindu Hasaranga, Lahiru Kumara, Janith Liyanage, Eshan Malinga, Kamindu Mendis, Pathum Nissanka, Mohamed Shiraz, Maheesh Theekshana, Jeffrey Vandersay, Dunith Wellalage, Chamidu Wickramasinghe.
