  Inspired by the increasing popularity of Swiss-system tournaments in sports,
we study the problem of predetermining the number of rounds that can be
guaranteed in a Swiss-system tournament. Matches of these tournaments are
usually determined in a myopic round-based way dependent on the results of
previous rounds. Together with the hard constraint that no two players meet
more than once during the tournament, at some point it might become infeasible
to schedule a next round. For tournaments with $n$ players and match sizes of
$k\geq2$ players, we prove that we can always guarantee $\lfloor
\frac{n}{k(k-1)} \rfloor$ rounds. We show that this bound is tight. This
provides a simple polynomial time constant factor approximation algorithm for
the social golfer problem.
  We extend the results to the Oberwolfach problem. We show that a simple
greedy approach guarantees at least $\lfloor \frac{n+4}{6} \rfloor$ rounds for
the Oberwolfach problem. This yields a polynomial time
$\frac{1}{3+\epsilon}$-approximation algorithm for any fixed $\epsilon>0$ for
the Oberwolfach problem. Assuming that El-Zahar's conjecture is true, we
improve the bound on the number of rounds to be essentially tight.
