The Vikings may not be standing still at slot cornerback heading into the 2018 season.

Currently with just 24-year-old Mackensie Alexander as an experienced nickel option under contract, the Vikings have expressed interest in at least one possible addition. Bryce Callahan, a Bears restricted free agent, is on Minnesota's radar, a league source told the Star Tribune, after the 26-year-old cornerback deflected two passes and returned a punt for a touchdown against the Vikings last season.

Curiously enough, the Bears only put the low-level restricted free agent tender on Callahan. That saved the Bears $1 million, but awards them no compensation should Chicago not match an offer made by another team. It immediately made Callahan a more enticing target for a team like the Vikings. He went undrafted in 2015 out of Rice, the alma mater of safety Andrew Sendejo.

He's not the only option on the market, but perhaps one the Vikings might snatch at their price. Rams free agent Nickell Robey-Coleman, 26, drew the Vikings' attention last offseason. He's a free agent again. Jaguars free agent Aaron Colvin, 26, is another experienced slot corner about to hit the open market.

The Vikings also have two free agents, Terence Newman and Marcus Sherels, who could likely return to the mix. Newman played well last season for the Vikings' No. 2 pass defense allowing 192 yards per game, but he'll be 40 in September. The Vikings also took a chance on Tramaine Brock, sending a seventh-round pick to Seattle for him last summer. He wasn't a factor.

The team's interest in Callahan or any other slot corners says more about Alexander, a former second-round pick entering his third NFL season. He spoke candidly about needing to mature early in his professional career and the Vikings have brought him along slowly. He barely played as a rookie and saw 323 defensive snaps [about one-third] last year.

Alexander has the talent and confidence to be a contributor. It's just yet to materialize on the field. He was one of the league's lowest-rated tacklers in NFL secondaries, making 12 and missing six, according to Pro Football Focus. Drew Brees also targeted Alexander for the 4th-and-10 conversion to Willie Snead in the NFC Divisional playoff game.

So the Vikings don't appear ready to hand the reins to him as they look around the league for help.