The rookie quarterback, who was picked in the first round of this year's Draft, had guided the AFC East side to two wins so far this year.
Horton told the Browns' website: "They've been in every game. Manuel's been showing a lot of poise under pressure. The kid is pretty unflappable.
"We think we're a little different style defense than he's faced, so it'll be a good challenge for us.
"He's not like an unprepared rookie where he makes a ton of mistakes. He's won two games already, which I give him credit for. Coach [Doug] Marrone is doing a great job of understanding what he can handle, and we're going to try our best."
The Browns host the Bills later today.