A circular knitting machine for knitwear, comprising a needle-holding cylinder, having longitudinal grooves housing a plurality of needles, and a needle-holding ring, having radial grooves housing a plurality of holding-down sinkers, and wherein each needles is paired with an adjacent sinker to form a needle-sinker assembly; the knitting machine comprises, for each needle-sinker assembly, a pre-selection element paired with the respective needle and comprising a connecting portion selectively cooperating with the sinker belonging to the same needle-sinker assembly; each radial groove has a rear section and a front section; the front section is wider than the rear section and configured for laterally containing and guiding the connecting portion of the pre-selection element.