The forward has joined from Villarreal on a permanent deal, after impressing on loan at Sheffield United during the second half of last season.
Now Diaz is excited to rekindle his partnership with former Blackburn Rovers teammate Adam Armstrong.
“I know a few of the boys that I played with at Blackburn,” Brereton Díaz said, having also played alongside Taylor Harwood-Bellis.
“Obviously Arma, I played with him for a couple of years at Blackburn, what an unbelievable lad. He’s done amazing things, scoring goals, he’s a great player and a great person, so I’m excited to see him.
“We were both a little bit younger at Blackburn, but we played a lot of times together, we had a good relationship there and I’m sure we’ll pick up where we left off and have a good relationship here as well.”