Ditto this. I don't know if Ibex still has any of these left, but they are great for this purpose.
I also have two of the lighter, flimsier, pointelle tanks that I wear under my cotton clothing to keep me warm. They seem too flimsy to wear for athletics, but they are great for layering underneath things. They are also low cut, so would not show under other items.
Lastly, Ibex has this balance sport top. I haven't tried it, but it might work for your purposes.
http://www.ibexwear.com/shop/Product...nce-Sports-Top