The influence of waves and in particular the effects of airflow separation is arguably the largest uncertainty in determining precise air-sea momentum fluxes for a variety of conditions. We present laboratory measurements of the velocity in the airflow above wind-waves. These data, obtained using PIV techniques, yielded the velocity within the viscous sublayer above the wavy surface. Concurrently, we estimate the surface viscous tangential stress in the airflow. The separation of the viscous sublayer past the crest of the wind-waves leads to the transport of vorticity away from the surface and the generation of significant mixing. The separation also causes dramatic along-wave variability of the surface stress and velocity. These results hold for wind speeds that would normally be considered benign. Furthermore, the statistics of separation events correlate with surface wave slope parameters. We compare the results with available theoretical predictions.