Sampras said Federer should be comforted by a streak that finally ended with a defeat to Rafael Nadal .
Sampras retired after winning his 14th Grand Slam title at the 2002 U.S. Open .
Sampras , who retired after winning his 14th Grand Slam title at the 2002 U.S. Open , said Federer should be comforted by a streak that finally ended with a defeat to Rafael Nadal .