That's more than Nadal has played Federer and only four fewer times than John McEnroe played Jimmy Connors (Andre Agassi and Pete Sampras also met 34 times).
The L.A. Tennis Open has been around since 1927, and has seen such great champions ranging from Pete Sampras, Andre Agassi, Boris Becker, Stefan Edberg, John McEnroe, Jimmy Connors, Jim Courier, and Michael Chang.