After trouncing one of the league’s presumed bottom feeders last Friday night in Jacksonville, the Dolphins travel to Houston tonight to play a legitimate Super Bowl contender.

While both teams figure to play their starters one quarter at most, it will be intriguing to see how the Dolphins match up with a team that beat them 30-10 last September, after an aggressive offseason approach to improve the roster.

There are also a couple of position battles with starting implications and several competitions on the back end of the roster to monitor. Here are my five keys to a successful third preseason game for the Dolphins:

1. No serious injuries

It goes without saying that the number one priority for the Dolphins in each of these exhibition games is not losing any players to injury, especially any starters or key contributors.

But we’re going to mention it anyway just to hammer home the idea that good health — above everything else — is what constitutes a successful preseason.

The team’s starters will play even more that they did in Jacksonville last week against the Texans on Saturday night before playing as many as three quarters in next week’s dress rehearsal. That only means there will be more opportunities for injury.

Escaping Saturday night in Houston and next Saturday night at home against the Buccaneers injury-free would put the Dolphins on schedule to be close to full health for the opener in Cleveland if the likes of Randy Starks, Dion Jordan and John Jerry can recover in time.

2. Show progress up front against a talented Texans front seven

J.J. Watt and the Houston Texans will provide a great test for the heavily scrutinized Dolphins offensive line. If Jonathan Martin, Tyson Clabo and Josh Samuda, in particular, can do an adequate job of protecting quarterback Ryan Tannehill against this team, perhaps they’ll be just fine this season.

If not, it could be an ugly night for an offense that has been struggling to establish any rhythm through two preseason games.

Ryan Tannehill looks unsure of himself at times behind Miami’s O-line. His confidence isn’t likely to improve in time for the regular season if he’s running for his life again tonight.

3. Confidence and decisiveness from Tannehill, involvement from Wallace

Speaking of Tannehill, the second-year quarterback hasn’t had the luxury of passing behind a reliable offensive line yet, but you can’t put all of the blame for the first team offense’s slow start on the big guys up front.

Tannehill threw two beautiful passes to tight end Dustin Keller during a touchdown drive against the Jaguars last Friday, but before those throws, he looked anxious in the pocket. Even when he had decent protection, Tannehill was quick to scramble instead of setting his feet to pull the trigger on open receivers.

Encouragingly, Tannehill had perhaps his best week of practice so far and appears poised to have his best game of the preseason to date.

Dolphins fans would also be ecstatic to see a big catch or two from Mike Wallace. I don’t think Tannehill necessarily needs to connect with the speed demon on a deep ball, but getting him involved in the offense should be made a priority tonight.

If I’m offensive coordinator Mike Sherman, I’m drawing up a couple easy completions for Wallace with a quick-hitting slant or screen.

4. First-team defense passes test from one of league’s top offenses

We may get a glimpse at exactly how good the Dolphins’ starting defense will be this season against an offense that finished seventh in the entire league in 2012.

The Dolphins looked the part against the lowly Jaguars, but any defense with a decent amount of talent can do that. Playing that well against the Texans would actually be something for Dolphins fans to get excited about.

I want to see how Brent Grimes handles a big receiver like Andre Johnson, if the Dolphins’ defensive line can shut down an athletic, zone-blocking rushing attack, how big of an impact middle linebacker Dannell Ellerbe has with more snaps and if Olivier Vernon is ready to emerge as a legitimate pass-rushing threat opposite Cameron Wake.

If Miami can keep Houston’s starters out of the end zone, the hype surrounding this defense as possibly an elite unit will only continue to build.

5. Contenders separate themselves from pretenders on roster bubble

There are several players who still have a shot at playing their way onto the team after impressing during the first two exhibitions.

At running back, Jonas Gray is three tough-running performances away from forcing the Dolphins to keep four players at the position.

At wide receiver, the Dolphins are still looking for a fourth and fifth option, although Rishard Matthews is back from injury and playing well at practice and Chad Bumphis has made his fair share of plays operating from the slot.

Will Yeatman at left tackle and Kheeston Randall at defensive tackle are two players who must continue to impress the coaches in the trenches.

The Dolphins are set with Dannell Ellerbe, Philip Wheeler and Koa Misi at linebacker, but depth for the corps is a concern. Can a Josh Kaddu or Austin Spitler make some plays to stand out from the pack?

In the secondary, Nolan Carroll must convince the Dolphins to keep six cornerbacks and a safety like Kelcie McCray will try to earn a spot behind Reshad Jones and Chris Clemons.

However it all shakes up, the Dolphins have concerns about their depth at numerous positions and want to leave Houston feeling much better about it.