Roger Federer has 13 victories in a row over Lleyton Hewitt in a six-year domination of their rivalry, but the World No 1 still respects the Australian as a threat to his reign at the US Open.

Federer has won five titles in a row and 37 consecutive matches at Flushing Meadows entering his third-round meeting with Hewitt, a former World No 1 who won the 2001 US Open title, at Arthur Ashe Stadium on Saturday.