It’s known as the “official dress rehearsal.”The third preseason game has a regular-season feel to it with starters on each team playing for an extended period of time. It’s the best test as to where a team stands two weeks before the season begins, which is why there will be more focus on the Dallas Cowboys on Saturday night than in the other three exhibition games.The Cowboys are expected to have their first-team offense and defense play multiple series, possibly the entire first half, against the Miami Dolphins in what should help forecast the realistic expectations for the 2014 Cowboys.1Tony RomoThe star quarterback will always be someone to keep an eye on. He underwent back surgery in December and one big hit could put the Cowboys’ season in jeopardy. But Romo, thanks to the strong offensive line, stayed upright for the most part in his preseason debut last week and showed little rust in two series. Another similar outing this week would help put some doubts to rest once again.2Middle linebackerWho is the starter? Justin Durant makes the most sense, but he might be more valuable on the weakside if Rolando McClain or rookie Anthony Hitchens prove to be capable replacements. It’s tough to rely on McClain at this point, though, as the twice-retired linebacker has missed several practices with various issues. And Hitchens is an unproven rookie who is viewed more as a development piece than an immediate contributor.3Brandon CarrThe starting cornerback makes his preseason debut. Carr believes he’s caught up to game speed but this will be his first real test. The question, though, is who starts opposite of Carr. Orlando Scandrick might, but he’s suspended for the first four regular-season games. Morris Claiborne will start in the regular season assuming he is healthy. Sterling Moore will play the nickel in the regular season assuming he is healthy. B.W. Webb is another option.4Surprise playersSafety Ahmad Dixon shined in the preseason opener against the San Diego Chargers. Then defensive lineman Zach Minter came out of nowhere with an eye-opening performance against the Baltimore Ravens last week. Both Dixon and Minter should get significant playing time this week and could become contributors. And it’s worth seeing if another unknown player steps up and puts himself in the mix.5Coverage unitThe return coverage was pitiful against the Ravens. It gave up a 108-yard kickoff return for a touchdown and another 50-yard kickoff return. Those mistakes must be fixed before the regular season, since winning the field position battle is vital with a suspect defense.