The Spirit made Wellington battle for its win last week and hopes to push Auckland just as hard at Colin Maiden Park today.
"We’ve certainly been getting better and better every game," McEwan said.
"We showed, particularly in the first half against Wellington last week, that we can actually compete with the very top teams. And that is what we are aiming for in Auckland. We really want to take it to them.
"The key thing for us is to make sure we don’t back off at all. We’ve had periods in every game where we have let in a couple, maybe three, soft tries because we just seem to lose our focus."
The Spirit will be missing talented first five-eighth Michaela Baker, who is unavailable due to university commitments, while lock Annemieke van Vliet has injured her ankle and back-up hooker Paige Church is unavailable, due to personal reasons.
American international Hannah Stolba returns to the starting XV in the absence of New Zealand sevens player Kelly Brazier.
Auckland coach Dean Bickerton has made several changes to his run-on side.
Injuries to Linda Itunu (foot) and Charlene Gubb (ankle) has promoted Shannon Willoughby and Charlotte Scanlan, while New Zealand sevens players Tyla Nathan-Wong and Theresa Fitzpatrick will get a start as well.
Auckland leads the competition with four wins from as many games.
It has scored 174 points, while conceding just 25, and will start as overwhelming favourite.
That said, Bickerton is still wary of the danger Otago presents.
"They have nothing to lose, and a lot to gain," Bickerton said.
"We know they will come out firing and are a team that is better than their results suggest."
Farah Palmer Cup
Otago v Auckland
Auckland, today, 11.30pm
Otago: Hannah Stolba, Kiana Wereta, Kilisitina Moata’ane, Greer Muir, Renaye Flockton, Olivia Waldron, Megan Manson, Rachel Ovens, Angie Sisifa, Georgia Mason, Julia Gorinski, Raewyn Gregory-Hunt, Gemma Tuhega, Tegan Hollows, Kirsten Shalosky. Reserves: Morgan Church, Eilis Doyle, Jess Kendall, Maddi Finch, Zoe Whatarau, Georgina McCullough, Kathryn Kibby.
Auckland: Tyla Nathan-Wong, Teuila Fotu-Moala, Theresa Fitzpatrick, Onjeurlina Leiataua, Mele Hufanga, Kiritapu Demant, Emma Jensen, Charmaine McMenamin, Lydia Crossman, Charlotte Scanlan, Shannon Willoughby, Eloise Blackwell, Doris Taufateau, Fiao’o Fa’amausili, Karina Stowers. Reserves: Aldora Itunu, Aleisha Nelson, Aimee Lenssen, Nora Baltruweit, Malia Tova, Aeron Warbrooke, Hasting Leiataua.