With Anthony Rendon on second base and Ryan Zimmerman at first, Chris Heisey lifted a one-out fly ball to left. Staring into a virtually cloudless sky, Williamson pursued the ball, which struck his glove but bounced away.
Williamson fell as he recovered the ball and had to twist his upper body as he forced a throw. Meanwhile, Rendon broke late for third, believing Williamson would make the catch. Williamson's toss skipped several times but had enough on it to force out Rendon.
Said Williamson, who immediately left the game, "I lost the ball a little bit in the sun. I tried to pick it up and my left arm was on the ground, kind of extended. It kind of went numb for a little bit."
Chris Haft has covered the Giants since 2005, and for MLB.com since 2007. Follow him on Twitter at @sfgiantsbeat and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.