United have paid the price for inconsistency this term as eight draws and three defeats in 22 league matches has left them 15 points adrift of Antonio Conte's men in sixth.
That fixture comes against rock-bottom Hull City on Wednesday and Herrera sees no reason why Jose Mourinho's men cannot catch the teams in front of them - even if overtaking Chelsea remains a target too far.
"At the moment, Chelsea are many points ahead and, to be honest, we have to think about second place right now," Herrera told United Review.
"We are six points behind second spot and, in the Premier League, anything can happen in two weeks. Any team could be second, third or sixth.
"We must win against Hull and not think about the rest or the next game. We just need to win and try to get into the top four as soon as possible, but we should have our minds focused on the fact that we can be in second place soon.
"It is Hull at this moment and we have an obligation to win if we want to be in the top four. It is going to be tough. It always is. Every Premier League game is tough. But we are at home, we feel strong and good in front of our own fans and we want to win.
"I will say it again, no excuses, we want to be in the top four as soon as possible."