Van Bommel rushed into a challenge with Ajax full-back Lucas Rosa after referee Serdar Gozubuyuk had already blown his whistle. The winger planted his right foot and buckled his knee as he set off again, visibly popping something in his knee.
The 21-year-old Van Bommel, who joined PSV last summer for nearly €16 million from AZ, screamed it out as he hit the grass and had to be supported off the pitch. The Netherlands Under-21 international was replaced by Esmir Bajraktarevic.
Father Mark van Bommel and grandfather Bert van Marwijk, who managed the Netherlands when they reached the final of the FIFA World Cup in 2010, looked on in the stands with worried faces as Ruben exited the derby against Ajax early.
Van Bommel's injury only worsens PSV's fitness situation. Manager Peter Bosz will have to do without strikers Alassane Plea, after he injured his knee badly against FC Twente in August, and Myron Boadu, who had to be taken off in last Tuesday's Champions League meeting with Union Saint-Gilloise with an upper leg injury and faces a six-week spell on the sidelines.
