Tom Brady is up to something. The 42-year-old quarterback — who is widely recognized as the greatest to ever do it — posted an interesting photo on his Instagram that indicated that his future with the New England Patriots and the NFL is in doubt.

Brady posted a picture of him walking out of a tunnel to social media. There was no caption.

Interesting picture, to say the least. It's a curious case. Brady has said on multiple occasions that he is not interested in retiring. However, the picture that he put up on social media is indicative of possible retirement. Interesting.

What does the picture mean? It could be retirement, or it could mean that he's thinking about leaving the Patriots or, perhaps, he just likes the photo and wants to freak others out on social media. Because that's what athletes tend to do now with their cryptic pictures and emojis.

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For now, the only thing to come out of the photo is that Brady uploaded it. One would be hard-pressed to assume that he did not do so for a reason. After all, he is a free agent for the first time in his 20-year NFL career in March.

If the photo means that Brady has his eyes set on leaving the Patriots, there should be plenty of suitors for him in free agency, despite his age. The Los Angeles Chargers, Indianapolis Colts, and Tennessee Titans currently have the best odds of signing Brady if he decides to leave the Patriots.