We present a complete ${\cal O}(\alpha_s^2)$ correction to the
differential width of the inclusive semileptonic decay $b\to cl\nu_l$
at the kinematical point of vanishing invariant mass of the leptons,
$q^2=0$. Together with the recently computed ${\cal O}(\alpha_s^2)$
correction at the upper boundary of the lepton invariant mass
spectrum, this new information permits an estimate of the ${\cal
O}(\alpha_s^2)$ effect in the total inclusive semileptonic decay width
$b\to cl\nu_l$. We argue that the non-BLM part of the ${\cal
O}(\alpha_s^2)$ correction gives at most $1\%$ correction to the
inclusive semileptonic decay width $b\to cl\nu_l$. This significantly
improves the credibility of extracting $|V_{cb}|$ from the inclusive
semileptonic decays of the $b$-hadrons.
