United welcome The Foxes to Old Trafford on Saturday afternoon as they look to return to winning ways in the division following a run of three games without a win.
“They're creative they have pace, there's good link-up between the two of them," the United manager told the official United app.
"One of the most productive partnerships and we know from last year that Maddison created loads of chances and to have Vardy's energy and penetration and running in behind all the time is great for any creative player.
"I think they're challenging for the top four. They've got quality players and a quality manager. I've admired Brendan (Rodgers) from afar at times and played against him - I was the manager at Cardiff when he was at Liverpool.
"He's got a very good philosophy and he wants his team to play good football. We know it's going to be tough but any game in the Premier League is hard."