Roger Federer has compiled a most impressive list of winning streaks, including the following.
- consecutive matches won on grass: 65
- consecutive matches won on hard court: 56
- consecutive wins against top 10 players: 26
- consecutive wins in North America: 55
- consecutive finals won: 24
- consecutive matches won in grand slam matches against players outside the top 5: 124
A streak which just ended for him was a 77-match winning streak against players ranked outside the top 20. On either side of these wins were losses to former world number ones in Lleyton Hewitt and Andy Roddick. He had 19 other losses during this time but they were all to players in the top 20 at the time. I looked here and found two other similar winning streaks for him:
- A 55-match winning streak against outside-top-20 players in 2008-9 (losses to Ivo Karlovic and Julien Benneteau on either side).
- A 78-match winning streak against outside-top-20 players in 2005-6 (losses to Richard Gasquet and Andy Murray on either side). Only one of his six losses during that time was not against Rafael Nadal!