Update: Source says Sanders' offer sheet is still awaiting a physical, and nothing will be official before that.

Multiple sources are hinting at Steelers wide receiver Emmanuel Sanders having received an offer from the New England Patriots in restricted free agency.

Getting word that Emmanuel Sanders has signed an offer sheet with the #Patriots. #Steelers will have a chance to match. No $/years yet. — Mike Gambardella (@BIG3Sports) March 15, 2013

Perhaps none are more suggestive than Antonio Brown, who strongly hinted at the Patriots having offered Sanders a contract he will sign, and the Steelers won't match.

Guess AB the last guy standing ! #SteelersNation — Antonio Brown(@AntonioBrown84) March 15, 2013

Nothing has been officially confirmed yet, and depending on the rules for conduct in these situations, the rumors could be nothing more than that.

#Steelers not be informed that Emmanuel Sanders been presented offer sheet by Patriots let alone signed one. Pats have to notify immediately — Mark Kaboly (@MarkKaboly_Trib) March 15, 2013

#Steelers WR Emmanuel Sanders very well could've signed RFA offer with Pats, but if he did, the Steelers haven't been informed yet. — Mark Kaboly (@MarkKaboly_Trib) March 15, 2013

Per our understanding of the CBA, if Sanders signs an offer sheet with another team, it is on him to formally present it to the Steelers. Once he has done so, the clock officially starts for the 5-day period wherein the Steelers can exercise their right to match.

Read more: NFL Collective Bargaining Agreement on Restricted Free Agent procedures

Sanders is a talented but injury-prone receiver, whom sources have told Behind The Steel Curtain the team wants to keep but won't match a deal offered from another team.

That same source said Arizona is also interested in Sanders' services.

Again, none of that has been officially confirmed, but considering the Steelers' cap position, it wouldn't be surprising if a team in significant need of receiver help (like Arizona or New England) made a moderate offer for Sanders' services, considering the Steelers cap situation.

We will continue to follow this story as it develops.