Context: The Redskins traveled to Bank of America Stadium to face the Carolina Panthers.  Washington scored with quarterback Jason Campbell completing a 10-yard touchdown pass to running back Clinton Portis.  The Panthers gained a safety in the second quarter as linebacker Thomas Davis and defensive end Julius Peppers tackled Portis in his end zone for a safety.  Afterwards, the Redskins closed out the half with a 38-yard field goal by kicker Shaun Suisham. Both Washington and Carolina scored touchdowns in the third quarter. The Panthers later scored on a 43-yard field goal from kicker John Kasay and an 8-yard touchdown run from running back Jonathan Stewart (along with Delhomme's 2-point conversion pass to wide receiver Steve Smith). With the loss, the Redskins fell to 2-3.  The Panthers got their first win of the season.

Question: Which players were responsible for the safety?

Answer:
Thomas Davis