Giants 10, Nationals 3: Joe Panik hit a three-run homer and Buster Posey added a solo shot as visiting San Francisco halted Washington's 10-game winning streak.Panik went 4-for-5 and belted his first major-league homer as the Giants remained 3 1/2 games behind the first-place Los Angeles Dodgers in the National League West. The Nationals saw their lead in the NL East dip to six games over the Atlanta Braves.Tim Hudson (9-9) allowed two runs (one earned) and five hits in 5 1/3 innings for his first win since July 19. Washington's Doug Fister (12-4) gave up four runs and seven hits in six innings. The Nationals had a 1-0 lead entering the fourth before Pablo Sandoval and Michael Morse singled with two out and Panik followed with a blast over the center-field fence to put the Giants ahead. Jayson Werth pulled the Nationals within a run when he led off the fourth with a line-drive homer to left.Posey homered with one out in the sixth to give San Francisco a 4-2 advantage and Travis Ishikawa ripped a two-run double off the wall in right-center field in the eighth to make it a four-run margin. The Giants blew it open with four in the ninth on Hunter Pence's run-scoring single, Posey's RBI double, Sandoval's sacrifice fly and Gregor Blanco's run-scoring single.GAME NOTEBOOK: Washington's 10-game winning streak matched the franchise record, accomplished four times previously with three of those occurring when the franchise was known as the Montreal Expos. … Panik has six multi-hit outings in the last seven games and is 15-for-27 during the stretch. … Nationals OF Nate McLouth underwent season-ending surgery to repair a torn labrum in his right shoulder.