Manager Ron Washington said earlier Saturday he believed Napoli could catch in a pinch and that Martinez wasn't needed.
The Rangers, though, determined that having only Torrealba and emergency catcher Brandon Snyder was too much of a risk.
Martinez is a former Cumberland University standout. He made his MLB debut last year with the San Diego Padres and was traded in the off season to the Rangers. Martinez is the first former CU player to reach the majors.
Martinez has spent the entire season with Round Rock, batting .262 (43-164) with two home runs, 10 doubles, two triples, 17 RBIs and 22 runs scored in 50 games.
The right-handed batter has hit .304 (14-46) against left-handed pitchers. He has caught 10 of 47 (21.3%) attempted basestealers in the Pacific Coast League with a .987 fielding percentage in his team-high 50 games behind the plate.Acquired in a Dec. 21 trade with San Diego, Martinez saw his only Major League action with the Padres in 2011, when he batted .203 with a home run and 10 RBIs in 22 games.