Benches emptied in Kansas City after a hard slide by Oakland's Brett Lawrie into Royals second baseman Alcides Escobar that caused a left knee contusion.
Lawrie tried to slide into second base, running from first on a Josh Reddick grounder. Lawrie's slide appeared to twist Escobar's leg.
As Escobar stayed on the ground for several seconds, Lawrie exchanged words with Royals players and the benches cleared.
No punches were thrown, and Escobar was helped off the field by teammates and staff. He did not put weight on his left leg as he left the field.
Escobar is a mainstay in the Royals' lineup. He played all 162 games last year for Kansas City, hitting .285 and launching three home runs.
Escobar is listed as day to day.
- Will Green