Tennis must be the sport with the highest rate of establishing patterns. Ok, you can say matchups make matches, and in soccer, Brazil had always problems with France, or Germany with Italy; or in boxing, Ali found his nemesis in Ken Norton. But its really astonishing, how results evolve along certain patterns. Nadal beats Fed at RG thrice, with very similar scorelines. Davydenkos match vs. Fed was a carbon copy of their AO 2006 match. Roddick wins zero, or at best 1 set against Fed. Also in some older rivalries you notice patterns: Sampras always beat Agassi at USO, at AO it was different. If you look at Mac-Lendl, you see, that both had long series of uninterrupted wins. Same for Borg-Connors. Sometimes the players seem to have the pattern internalized, the patterns seem to shape their mind before or even inside their matches.