Knesers conjecture, first proved by Lovász in 1978, states that the graph with all k-element subsets of {1, 2, . . . , n} as vertices and with edges connecting disjoint sets has chromatic number n–2k+2. We derive this result from Tuckers combinatorial lemma on labeling the vertices of special triangulations of the octahedral ball. By specializing a proof of Tuckers lemma, we obtain self-contained purely combinatorial proof of Knesers conjecture.