Brook returned from an horrific stab wound to make a mandatory defence of his belt in March – delighting his home fans in Sheffield by stopping Jo Jo Dan inside four rounds and stretching his unbeaten record to 34 fights.
But domestic rival Gavin, who is Britain’s only ever world amateur champion, is adamant he can spring a surprise.
The 29-year-old told Sky Sports News HQ: “When it first got announced, I was over the moon but now I’m on the business side of it – training very hard, harder than I’ve ever trained.
“I expect to come out on top. I know Kell Brook is a great fighter but I can beat him. I’ve got the style to beat him.
“I’m doing a lot of different things and training with more intensity, pushing myself to boundaries I’ve never pushed myself to before. I really think I’m going to surprise a lot of people on May 30.
“I expected to be here a bit earlier than I am. I had a few problems early in my career. I think it’s the right time and I’m as ready as I’ll ever be. I really do think I’m going to win this fight.
“I’m a good counter-puncher and I think technically I’ll be the best fighter Kell will have been in with. I think many would agree.
“Obviously, people say I’ve got a lot more than I’ve shown. When I’m winning, I just like to win when I could do a lot more. On the 30th, I’m going to have to do a lot more but I’m going to give him problems he’s never faced before.”
Gavin lost his own unbeaten record last summer when he suffered a split decision defeat to Leonard Bundu in Wolverhampton – but rather than damage his confidence, the Birmingham man believes he has learned a valuable lesson from the loss.
Gavin added: “Before you’ve lost you are so keen on protecting your ‘0’ that you forget about other things. I’ve proved a lot of things to myself – when it gets tough I can go with it. I showed my heart and battled through and took over towards the end of the fight.
“A lot of people thought I won. Some thought he won. It was very close. There was only a point in it at the end and it could’ve gone either way. If anything, it’s given me strength and I’m not really thinking about the loss now.
“This is no foregone conclusion. I can understand him looking past me because he’s the champion but I’m coming to take his title and push him as far as I can. Hopefully that’s enough.”