The team is encouraging fans to bring dog masks to Lincoln Financial Field in Philly on Sunday -- to keep the whole "underdog" theme going as they face the Vikings.

Of course, Chris Long essentially started the dog mask thing by rocking a German Shepherd head after they beat the Falcons this weekend.

Now, the team has sent a message to fans -- "Doggone it, you better believe dog masks will be allowed at @LFFStadium this weekend. Just make sure to take them off when you go through security."