Photo - Aj Mansour (KFAN)

By: Aj Mansour | KFAN.com
@AjMansourKFAN

Minneapolis, MN - Yes the preseason is just the preseason and the games don't really matter all that much, but it's still football right? Friday night the Vikings welcome Philip Rivers (update, Rivers is OUT) and the San Diego Chargers to Mall of America Field for preseason game number three. While the final score doesn't matter one lick, here are some things that you should be watching during tonight's Vikings' game.

Starters will play through the entire first half and into the third quarter...
Head Coach Leslie Frazier confirmed tradition earlier this week announcing that the Vikings plan to keep their starters in the game through the entire first half and potentially one drive into the third quarter. Christian Ponder and the Vikings first team offense has yet to punt this preseason scoring on all but one of their five drives to date (Blair Walsh missed 49-yard field goal). While proving to be effective, the first team offense still has a lot to prove before they will be taken seriously by the opposition. Look for Christian Ponder to continue his consistent, game managing style of play as he continues to progress into a legit NFL quarterback.

Vikings punt return slot remains vacant...
With most of the coach's pencil marks turning into ink, one spot that remains open is the punt return slot on the special teams. Marcus Sherels, Josh Robinson, Stephen Burton, Bryan Walters and Jarius Wright have all returned punts for the Vikings so far this preseason. Sherels is the incumbent candidate and likely the current leader in the clubhouse. While Sherels is not necessarily the most explosive kick returner, he might be the most reliable. "The guy I'm most comfortable with back there would be Marcus Sherels," special teams coach Mike Priefer said Tuesday. "He's done it before and he is a very sure handed guy." While Sherels will take first team returns tonight against San Diego, Marcus's grasp on his secondary position of cornerback is slipping. When each of the 53-man roster spots carries such high value, the Vikings may look for a guy like Stephen Burton who will likely make the team as a receiver to step in and return punts this season.

Vikings keying in on rookie CB Josh Robinson...
After rehabbing a lingering hamstring injury through most of Training Camp, rookie cornerback Josh Robinson took to the field for the first time last week against Buffalo and impressed the coaching staff. "I really like some of the things he did," Frazier said of Robinson after the Buffalo game."Friday night he did a good job of breaking on the ball, had a really big hit on that caused fumble that Chris Cook had. That was a heck of a hit by Josh. It was good to see a guy playing corner for us, attack the way he did."

Robinson's claim to fame to-date involves his impressive speed. The fastest player in the 2012 NFL Draft, Robinson posted a 4.33 sec 40-yard dash at the 2012 NFL Combine. With Chris Cook missing Friday's game with a concussion, repetitions will be available at the cornerback position tonight. Robinson showed impressive closing speed after getting beat deep in coverage and looks to use that speed against Rivers and a pass happy Chargers offense.

Players with the most to prove in preseason game number three...
Preseason game number three is likely the last time that we will see "starters" play before week one against Jacksonville. With that said, there are still a handful of "starters" that have left themselves in a position with much to prove.

Brandon Fusco (G) - Fusco had a tough night last week against a tough Buffalo Bills defensive line. Truth be told, an offensive lineman's bad plays stick out like a sore thumb compared to their good plays which are largely overlooked. That said, Fusco got run over multiple times last Friday evening. Still a second-year player, Brandon needs to take the field against the Chargers and prove that he has earned the starting slot at right guard and wasn't simply handed the job when Geoff Schwartz went down during Training Camp. Fusco will be squaring off against Antonio Garay, a 32-year old veteran who may not show Fusco great speed but will bring a crafty veteran twist to the experience tonight.

Jasper Brinkley (MLB) - It's probably not a good sign when you are heading into your final preseason game and your coaches continue to say that you are still "knocking off some of the rust" from sitting out the entire year last season. So far this preseason, Brinkley has looked slow. With two seasons and only 48 tackles under his belt, Brinkley was handed the job upon E.J. Henderson's departure and has yet to prove his worth. Coaches are beginning to chatter about backup MLB Marvin Mitchell who will be playing with a lot to prove the final two weeks of the preseason.

Josh Robinson (CB) - We mentioned Robinson above so I'll be brief here. Robinson is fast, he flashes and he will see significant time tonight with Chris Cook's injury. If Robinson is going to make and contribute to this team, his role will come from his effectiveness on the defensive side of the ball.

The Vikings vs Chargers from Mall of America Field will once again be simulcasted on KFAN 100.3FM and Kare 11 TV, kickoff at 7:00pm.

Aj Mansour covers Minnesota Sports for KFAN.com. Feel free to leave comments and questions regarding this post in the space provided below. For Vikings' updates and breaking Vikings' news, follow Aj on Twitter. @AjMansourKFAN