Beatmatching tracks of nearly identical speeds

I’ve been using Audacity for years and I know how to make acapellas easily but I’m stumped on this latest one -

I have two tracks - an instrumental, and the original song I want to make the acapella from. They’re both from the same cd single. The only problem is that they’re not exactly the same speed. They’re very, very close - one is only slightly faster than the other, but they’re different enough that filtering - whether with phase cancellation or kn0ck0ut - only sounds good briefly. I’ve tried adjusting the tempo, but Audacity isn’t allowing me to change it as specifically as this scenario requires. I’ve tried syncing them up in FL studio, but it won’t allow me to change it as specifically either. I’ve tried beatmatching in Virtual DJ as a last resort, but this isn’t coming up with anything usable either.

Any advice would be greatly appreciated.

By selecting the measurement technique you want within the tool, I think Effect > Change Speed should be able to let you adjust down to individual digital samples if you want. (click the graphic)
Screen Shot 2017-11-18 at 19.55.16.png

Now the cold water.

Cancellation techniques almost never work. Somebody, somewhere though it was a good idea to make one really tiny change to one version without applying the same change to the other. Or you could be listening to two different studio mix desks with slightly off sampling frequencies. Or you could be experiencing a malicious producer who thought they’d mess with you.

You already know you can’t do this trick right out of the gate with MP3. Each MP3 is a completely unique file.

You know the next step is finding the two ends match, but not the middle?