Marat Safin of Russia got down on all fours and kissed the ground at Arthur Ashe Stadium yesterday, and kissed away America's Pete Sampras's era at the U.S. Open. The "Russian Rocket," 20, beat Sampras in the Open Finals in a stunning 6-4, 6-3, 6-3 victory in some 98 minutes. "He reminded me of 10 years ago when I was 19 and first won here," Sampras said afterward. And on Saturday -- or Super Saturday, as far as Venus Williams, 20, was concerned -- Venus answered Lindsay Davenport's powerful ground strokes with her usual grace and added the U.S. Open crown to her Wimbledon title. It was her first at Ashe Stadium, but her second Grand Slam victory and her 26th consecutive match victory.