While trying to beat out an infield single in the top of the first inning, Bryce Harper slid on first base and landed awkwardly on his left leg.
On the play, Jones fielded the ball and beat Harper to the bag as pitcher Jeff Samardzija raced over to cover the bag just in case.
Harper flew in the air and appeared to be in agony as he hit the ground while clutching onto the front of his knee. The star outfielder put no weight on his left leg as he was helped off the field by hitting coach Rick Schu and head athletic trainer Paul Lessard. The base may have been slippery following a three-hour rain delay. He is among the National League's leaders in batting average, home runs and RBIs this season.
Andrew Stevenson took over in center field and Brian Goodwin moved to right field.