The secondary is the second most important unit to watch during training camp behind the offensive line. There are many questions at cornerback and safety for the Vikings, though they do have options at both positions.

The Vikings have two blue chip pieces in the secondary in Xavier Rhodes and Harrison Smith. They're are deeper at cornerback with the addition of Terence Newman and Trae Waynes through free agency and the draft. It's unsure at this point who will start opposite of Rhodes and who will be used in the nickel.

The Vikings added safety Taylor Mays in free agency, but he was cut right before minicamp. Undrafted rookie free agent Anthony Harris was the only addition this offseason at the position as the Vikings seek a safety to pair with Smith. They'll likely need to find that starter from a trio of players that were on the roster last yar.

We continue our Vikings training camp preview by analyzing the secondary.

SAFE BET STARTERS: Xavier Rhodes, Harrison Smith

Two of the best players on the Vikings are located in the secondary. Smith was the best player on the team last season and arguably the second best Vikings player on the roster heading into camp behind running back Adrian Peterson. He's capable of operating at both safety positions with his versatility as a blitzer and a cover safety. He has a very mellow personality, but Smith is very tough. He walked out of Lambeau Field last year in a walking boot after injuring his left ankle in a blowout loss to the Packers in Week 5. Smith still played every snap against Green Bay, and he played every snap the following week against the Lions despite wearing the boot for most of the week.

Rhodes took a big step forward last season flashing his potential as a lockdown cornerback. He thrived in head coach Mike Zimmer's defense, and he even received the opportunity to shadow the best wide receiver in the NFL for a game in Calvin Johnson. He's another key piece — along with Smith, defensive end Everson Griffen and linebacker Anthony Barr — on this defense that will need to continue to improve in order for the Vikings to have a top 10 defense this year.

BACKUPS: Captain Munnerlyn, Trae Waynes, Terence Newman, Jabari Price, Shaun Prater, Josh Robinson, Marcus Sherels, DeMarcus Van Dyke, Justin Coleman, Jalil Carter, Robert Blanton, Antone Exum Jr., Andrew Sendejo, Anthony Harris

CAMP BATTLE TO WATCH: Right guard and strong safety are the two biggest question marks heading into training camp. Blanton won the starting strong safety job by default last year despite suffering a hamstring injury during training camp. Andrew Sendejo finished the last three games of the season as the starter, however, even after Blanton recovered from a leg injury during the final month of the season.

The Vikings didn't use one of their 10 draft picks on a safety despite the glaring hole at the position. Exum is a big reason why, as we found out after the draft from general manager Rick Spielman. Exum converted from a cornerback at Virginia Tech to a safety in the NFL, and the Vikings are still high on the sixth round pick in 2014. He's expected to be in the mix with Blanton and Sendejo.

THE BURNING QUESTION: Fans expect first round picks to have an immediate impact as rookies, but the cornerback position is one of the most difficult positions to play in the NFL. So how exactly will Zimmer use Waynes this season? The Vikings tried Waynes out not only as an outside cornerback but in the slot during OTAs and minicamp while Captain Munnerlyn was sidelined in a walking boot. The 11th overall pick likely won't start immediately, but Waynes will get some opportunities to receive snaps this season. Zimmer has raved about how coachable Waynes has been since his Pro Day at Michigan State. We'll see how quickly he can catch on to Zimmer's technique and scheme.