SAN FRANCISCO -- Mac Williamson hit a two-run homer in the sixth to lead the Giants past the Washington Nationals 4-2 on Monday night. Chris Stratton (2-1) struck out five over 6 2/3 innings, allowing two runs and four hits. Williamson, playing his first home game at AT&T Park this season after being called up during the recent road trip, connected with a deep drive to right-center off Shawn Kelley after he relieved starter Gio Gonzalez (2-2).