The author proves the following result: Let \(f\) and \(g\) be two nonconstant meromorphic functions. Let \(a_1,\;a_2,\;a_3\) and \(a_4\) be four distinct small meromorphic functions with respect to \(f\) and \(g\). If \(f\) and \(g\) share \(a_1,a_2\) CM* and share \(a_3, a_4\) IM*, then \[ f=\frac{\alpha_1 g+ \beta_1}{\alpha_2 g +\beta_2}, \] where \(\alpha_i,\;\beta_i(i=1,2)\) are small meromorphic functions with respect to \(f\) and \(g\). Note that any CM (or IM) shared small function must be an CM* (or IM*) shared small function, where CM (resp., IM) is the abbreviation of counting multiplicity (resp., ignoring multiplicity). This fact generalizes many well-known results due to \textit{G. G. Nevanlinna} [Acta Math. 48, 367-391 (1926; JFM 52.0323.03)], \textit{R. Gundersen} [Trans. Am. Math. Soc. 277, 545-567 (1983; Zbl 0508.30029)], and so on.