UPDATE: Joe Nathan suffered a torn ulnar collateral ligament (UCL) on Wednesday and will require Tommy John surgery, the the Detroit Tigers announced Thursday.

Things are not looking good for the back end of the Detroit Tigers' bullpen. Their closer perhaps suffered a serious setback on Wednesday and it may force them to explore options outside of the organization. Rumors regarding the team going after another reliever surfaced even before this incident.

According to James Schmehl of MLive.com, closer Joe Nathan left today's rehab outing early after suffering an apparent injury. He was scheduled to throw 25 pitches at Triple-A Toledo, but he said he felt like he "broke his arm" after just 10. The right-hander claims to have felt a pop, but he's not jumping to any conclusions right now.

"I don't want to speculate on what this could be or what it is until we go get some photos taken," Nathan told Schmehl.

The veteran suffered a flexor strain in his throwing elbow on April 7 and has not pitched in a game since. He's eligible to return from the disabled list today and he said on Monday there was a chance he could be back with the Tigers on Friday. However, it doesn't look like that will happen, and Nathan could miss an extensive period of time if he's seriously injured.

As a result, the team may have to look for options around the MLB because their bullpen is already short-handed. Earlier this month it was said Detroit was keeping tabs on free-agent reliever Rafael Soriano, but not much has developed since then. Perhaps the bullpen's 2-0 record with a 3.41 ERA, 1.17 WHIP and .216 opponents' batting average didn't have general manager Dave Dombrowski in panic mode yet.

However, Nathan's setback may have changed that thought process and the team could make a drastic move. Is a trade for Philadelphia Phillies closer Jonathan Papelbon in the cards?

"Papelbon is the best closer available on the present trade market, and teams like the Blue Jays, Rockies, Reds, Indians, Tigers and Marlins could certainly use him to improve the back end of their bullpens," writes ESPN's Jim Bowden.

The right-hander has been the subject of trade talks for much of the offseason because the Phillies are looking to rebuild and have no need for an expensive closer such as Papelbon, who has been one of the best in the MLB over the years. Philadelphia was in discussions with the Toronto Blue Jays and Milwaukee Brewers about a trade, but the talks fell through and nothing ever came to be, mainly because of financial disagreements.

Being that Detroit is perhaps one good bullpen move away from reaching the World Series, it's certainly realistic they take on Papelbon's $13 million salary for 2015 as well as his $13 million vesting option for 2016 (which kicks in if he finishes 48 games this year).

Detroit has the fifth-highest payroll in the MLB, so inheriting Papelbon's contract isn't out of the question. We'll provide updates regarding Nathan's injury to determine whether or not the Tigers are considering a move and bolster their bullpen.