The Scots are facing Russia and Belgium in two key games that will decide their fate.
They are currently fourth in Group I, but McTominay has faith they can qualify.
He said to reporters: "You just have to take each game as a cup final, and it's vitally important for us to keep building on the progress we've shown under the new gaffer and I feel like it's two big games where you can look at it in two different ways.
"It's a must-win and it's definitely a must-not lose as well, so I feel like you have to take responsibility on the pitch first and foremost.
"We're not going to settle for anything less than us going and having a right go, but obviously that's up to the manager and the coaching staff with how they set us up and the different ways that they want to approach the game."