Barcelona coach Ernesto Valverde is planning a double raid on the Premier League to boost his midfield.
Valverde is fond of Ozil and Herrera and thinks they will be perfect additions to his new-look Barca.
The La Liga giants reportedly attempted to sign the pair over the summer but both deals failed to materialise.
However, now the Spanish side are faced with the attractive prospect of getting them both for nothing.
Herrera has spoken of his admiration for Valverde, having worked for him at Athletic Bilbao.
"He's a very smart manager who doesn't have one style of football. He adapts himself to the players' abilities," he said.
"I was with him for only one year but I really enjoyed it. He is very sincere, very transparent and I think he's going to be very successful there."