"I'm looking at it from a positive point of view," Herrera told Spanish newspaper Marca. "They're going to make us do better ourselves.
"Historically, City have always been below United, and this gives them a psychological advantage, because they are coming from behind.
"With Pep, with the multi-million pound outlay they've made and will spend with him, I expect the pressure to be higher for them. The fans are going to expect a lot, that they win the Premier League with a 10-point gap, that they reach the Champions League final.
"Pep seems a phenomenon to me. His teams always entertain me a lot, but at City the expectations will be very big."