In response to a question regarding the potential of AMDs Mantle API, industry veteran John Carmack stated that Nvidias OpenGL extensions can offer similar improvements over DirectX.
via N4G: pc news feed http://n4g.com/news/1370390/john-carmack-nvidias-opengl-extensions-and-amds-mantle-offer-similar-improvements-over-directx
via N4G: pc news feed http://n4g.com/news/1370390/john-carmack-nvidias-opengl-extensions-and-amds-mantle-offer-similar-improvements-over-directx