Harry Williams and Danny Wilson are United supporters from North Wales and arrived in the Swedish capital shortly before news broke of the Manchester bombing.
"It is absolutely shocking. I think everyone will be a little on edge on Wednesday," they tell Radio Sweden.
Ian Alletson, a united supporter from Manchester, was on board a ferry when he first heard the news.
"We found out this morning. It is an atrocity and we are thinking about everyone back home. I think it will take the edge off the game tomorrow. It shows there are more things in life than football," he says.
Another fan, Liam Alvey, is in Stockholm with his mother. He says Monday night's suspected terror attack in Manchester, means he will be more cautious at tomorrow's game.
“It makes you wary and cautious... It's not like you think something will happen, but it's always in the back of your mind. So from that perspective you do approach the game in a different way. But at the end of the day, you just want go and enjoy it and have a good night no matter what happens."
Liam Alvey, a Manchester United fan, spent Tuesday afternoon at the fan zone set up in central Stockholm. His mother, Ruth Alvey, said she was shocked when she learnt about last night's attack on the news.
“It's not what you hope to wake up to and it's not what you hope to see, so it was a total shock really. It seems so pointless. For terrorism there's no valid reason ever, but [targeting] kids at a concert? Come on, that's just going over the line.”
Opposing Ajax fans also started to arrive in Stockholm, Tuesday.
One group tells Radio Sweden that they "stand united together" with the Old Trafford club after the Manchester bombing, but Ajax "will still win the game".