St. Louis Cardinals manager Mike Matheny is "embarrassed" following Monday's revelation that pitcher Carlos Martinez's Twitter favourites list, which is public, had links and images to hardcore pornography.

"We're embarrassed and he's embarrassed," Matheny told the St. Louis Post-Dispatch at the Cardinals' spring training home in Jupiter, Fla.

The Cards manager warned his players for the third time Tuesday to be vigilant and conscientious on social media after Deadspin.com posted a video showing the long list of porn on his Twitter account.

The team was unable to contact Martinez until Monday evening, helping him remove the images.

Matheny spoke privately with Martinez about what he does on the social media site can be very concerning if viewed by a young fan.