Herrera - who was named the Red Devils' player of the year last season - started an online war by posting a video of him playing beach football and trying out his goalkeeping skills. However, United failed to reach an agreement with Los Blancos over his transfer fee and instead signed Lukaku in a deal worth around £75m.
Man Utd are reportedly set to secure midfielder Ander Herrera's long-term future at the club with a lucrative new contract offer for the Spaniard.
"There's no truth to Barcelona because I'm very happy at United".
Real Madrid appeared to have ended their interest in De Gea earlier in the summer after it became clear Zinedine Zidane is happy with his goalkeeping options.
The club's first competitive match of the new campaign will also be against Real Madrid in the European Super Cup on August 8, however, and Herrera is already looking to the clash in Macedonia.
'I prefer to have him with me, so I will do everything possible to have him here'.
The Spaniard told Spanish radio station Cadena Cope: "I think De Gea is going to stay". "He was really close to signing", he said after Sunday's win over LA Galaxy. We do not determine what the price is of a player of Real Madrid, Real Madrid do that. "We've signed an important player in attack and it's hard but you never know", Mata told Cadena Cope.