  In this paper we establish Lebesgue-type inequalities for $2\pi$-periodic
functions $f$, which are defined by generalized Poisson integrals of the
functions $\varphi$ from $L_{p}$, $1\leq p< \infty$. In these inequalities
uniform norms of deviations of Fourier sums $\| f-S_{n-1} \|_{C}$ are expressed
via best approximations $E_{n}(\varphi)_{L_{p}}$ of functions $\varphi$ by
trigonometric polynomials in the metric of space $L_{p}$. We show that obtained
estimates are asymptotically best possible.
