  We present the recent developments in the precision studies of W-pair and
single-W processes in e+e- collisions achieved with the help of the KoralW and
YFSWW3 Monte Carlo generators. We focus on the theoretical precision of the
measurements of M_W and anomalous couplings on the example of lambda coupling.
We present the mechanism of running these two independent codes in the form of
one Concurrent Monte Carlo code. We describe also the extensions of KoralW
necessary to emulate the kinematical region of single-W process.
