The heater from Houser in the top of the third inning knocked Russell's batting helmet off and sent him to his knees.
Russell stayed in the game briefly, taking first base after he was checked out by medical personnel then stealing second and eventually scoring.
But he exited in the bottom of the inning to be replaced at shortstop by David Bote.
The Cubs were already without star infielder Javier Baez, who could miss the remainder of the regular season with a hairline fracture of his left thumb.
Baez, who was batting .281 with 29 home runs and 85 runs-batted-in this season, was to be examined on Monday by a hand specialist to determine the likely length of his recovery period.
With the defeat the Cubs slipped 4 1/2 games behind National League Central leaders St. Louis, who will play the Cubs seven times in the final 10 games of the season.
The Cubs are now three back of the Washington Nationals, who occupy the NL's top wild card spot, and the Cubs are just 1 1/2 games ahead of the Arizona Diamondbacks in the race for the second NL wild card.