Lithium abundances in main-sequence F stars and sub-giants
  The application to main-sequence stars of the rotation-induced mixing theory in the presence of mu-gradients leads to partial mixing in the lithium destruction region, not visible in the atmosphere. The induced lithium depletion becomes visible in the sub-giant phase as soon as the convective zone deepens enough. This may explain why the observed " lithium dilution " is smoother and the final dilution factor larger than obtained in standard models, while the lithium abundance variations are very small on the main sequence. 
Jose Dias do Nascimento Jr, Sylvie Theado and Sylvie Vauclair