“Manchester United are coming to town and it doesn’t come any bigger – it’s a fantastic fixture for us,” he said.
“I know that the whole town of Middlesbrough will respond.
“A sell-out crowd, live on TV, red and white everywhere - it has the makings of a fantastic atmosphere.
“The players can’t wait to cross that white line and get on with the game.”
Having taken temporary charge of Boro before, Agnew says he is confident of delivering as Boro’s Head Coach.
“If it’s an audition, then that’s fine. This time, I feel ready and capable,” he said.
“It’s something I’ve always wanted to do and it’s the biggest challenge of my career.
“I have a clear view of exactly what’s needed and that’s what I aim to deliver. I do believe we will stay in the Premier League.”
Agnew says that he and his players know the test that Manchester United – unbeaten in 17 Premier League games - will pose.
“You can never underestimate a coach of Jose Mourinho’s quality, or a team of players that represent their club,” Agnew said.
“They are missing some top players but whoever comes in, they have an abundance of talent. We’re under no illusions it’s going to be a difficult game.
“But our players will give everything to the cause and I have no doubt that it will be the same again on Sunday.
“They are desperate to keep the club in the Premier League and they’ll give every ounce of what they’ve got.”