Assuming that they both have 11 official at bats in the 3 weekend games, which is about what they have averaged in such a span this year, here's the minimum Mauer needs to do to win the batting title:

If Cabrera goes 7 for 11 or worse, Mauer needs to get at least 2 more hits than him to win outright.

If Cabrera goes 8 for 11, Mauer can tie Cabrera by going 9 for 11.

If Cabrera goes 9 for 11 or better, Mauer can win outright by getting at least one more hit.