As the first week of 2018 NHL free agency draws to a close, Erik Karlsson remains an Ottawa Senators defenseman, but at least a half-dozen teams, including the Atlantic Division champion Tampa Bay Lightning, could still be hard after the All-Star.

After their 2017 offseason splurge, the Dallas Stars are the front-runners for the 10th-year blue-liner, according to The Athletic's Sean Shapiro. But Joe Smith, also of The Athletic, reports at least four other teams -- the Columbus Blue Jackets, San Jose Sharks, Lightning and Vegas Golden Knights -- have talked trade with the Senators. The Ottawa Sun's Bruce Garrioch, meanwhile, reports the New York Rangers and Washington Capitals have also been in touch with the Sens about a deal for Karlsson.

And the Lightning, perhaps in the hottest pursuit of them all, are even part of three-way trade discussions so as to afford Karlsson, according to TSN's Travis Yost.

TSN's Mike Kelly suggested before the July 1 start of free agency that landing in Vegas was the most "likely scenario" for Karlsson. That could still be the case considering the Golden Knights pursued the two-time Norris Trophy winner during the 2017-18 season and remain among the league's top teams in terms of salary-cap space.

But there are apparently no shortage of competitors for the big-name trade chip, and Smith cited an Eastern Conference executive Wednesday in reporting that Tampa Bay general manager Steve Yzerman, having swung and missed on John Tavares in free agency, will be in on Karlsson talks "with both feet."

That might require some serious maneuvering since a Karlsson trade could precede a long-term contract extension and the Lightning have the fifth-smallest amount of cap room in the NHL, according to CapFriendly. And that's why multiple teams could actually be part of a deal, as Yost reported Thursday.

A two-time 20-goal-scorer whose offensive production from the blue line has long made him one of the game's top D-men, Karlsson is entrenched as a face of Senators history. On a team that's committed to the rebuild, however, he's long been speculated as a trade target -- and a potential over-the-hump cure for contenders like the Lightning.