The model posted a photo wearing a United top along with black knickers and suspenders.
The Faroe Islands-born fan, who now lives in Copenhagen, regularly gives her opinion on the comings and goings at Old Trafford.
She doesn’t think that United should get rid of Ole Gunnar Solskjaer right now despite the team falling short of expectations.
Katrina wrote: “Sooo Jose is the new manager at Tottenham and Poch got fired!
“Well what does this mean for United? Will we get Poch as manager now? I don’t know. Only time will tell!!
“Poch is an amazing manager but I do still believe in Ole! How are you guys feeling about this?
“Do you think Ole should get replaced with Poch?”
Katrina had over 5,000 likes for her post.
One fan replied: “Wait this isn’t fair. How am I supposed to think with my brain when you in your outfit is just…”
Last week Katrina had shown her support for Solskjaer by posting a pic wearing just a United shirt with the Norwegian’s name on the back.
After a shock move to sack Pochettino last Tuesday, former United boss Mourinho was quickly installed at White Hart Lane.
United fans remain unhappy at the club’s form this season with the team lying seventh in the Premier League and 18 points already off top placed Liverpool.
Pochettino has been frequently linked to Old Trafford but there are now several clubs interested in him including Bayern Munich.