Garnacho is well aware of Forest's struggles under their new manager Ange Postecoglou.
"It’s a hard moment for them, but you never know in football," he told the club's website. "They may not have been winning games, but they have good players and will want to win. We have to be ready.
"We are in a good position in the league (five points off top spot), especailly after we had a little bit of bad luck with red cards. For example, the game against Brighton, we should win that game. And the game at United, if we play 11 against 11, I feel we would be on top.
"But we are okay. I think it's important to build from the last win against Liverpool and try to win again to be up there."
The 21 year-old added: "I think we have a team that can fight in the league and for the rest of the trophies, and we want to try to win at least one trophy. Because of the moment of the team, of the club, I think we can fight for the big trophies. It's the dream we have."