Both sides head into the game after Premier League defeats, but Monk believes Arsenal's 6-0 humiliation against Chelsea makes them a dangerous opponent.
Arsenal conceded four goals before half-time at Stamford Bridge as they lost ground in the title race, with leaders Chelsea now seven points ahead of them at the top.
Swansea, who were beaten 3-2 at Everton on Saturday, have not tasted victory in the top flight since a 3-0 win over rivals Cardiff City at the start of February, leaving them just four points clear of the relegation zone.
And Monk is anticipating a tough assignment in north London as his team look to end their eight-match winless run in all competitions.
"We expect a reaction from them," said Monk. "They're up there in the league and pushing for a different reason (to Swansea) and we expect a reaction from them.
"That's the message to my boys this morning and we'll try and go up there with the right attitude and put on the right performance to come away with something.
"But it's a very tough game, very tough team and we're in for a very, very hard night."
Despite their recent slump, Monk is confident his side can end their recent wobble and climb away from the drop zone.
"Their attitude is spot on," he added. "I'm confident with this bunch. They're confident that we can get out of this situation.
"It's not as if we're chasing trying to climb and chasing teams ahead of us in terms of points.
"It's in our own hands and we have to make sure and be very careful we don't make mistakes and cut them out of the games as quickly as possible."
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