Andy Ruiz punches Anthony Joshua during a heavyweight championship boxing match in New York. Photo: AFP

World heavyweight champion Andy Ruiz Jr said he was the more skilled fighter and Briton Anthony Joshua will have to rethink his strategy in their ­December 7 title rematch.

Mexican-American Ruiz produced one of boxing's biggest upsets when he dethroned the previously undefeated world champion Joshua with a seventh-round stoppage at New York's Madison Square Garden in June.

Their second WBA, IBF and WBO title showdown - dubbed the "Clash on the Dunes" - takes place in Saudi Arabia ­after former Olympic champion Joshua triggered a rematch clause and Ruiz said the fans can expect "fireworks" when they slug it out again.

"He's going to try to make adjustments. I don't know if he wants to exchange punches, but I'd love for him to do that because I'm the more skilled boxer," Ruiz said in an interview published on Saturday by The Telegraph.

"He'll try to box me round and use his jab. But for how long? How long can he keep me away from hunting him down? That's what we've been working on most of all right now, heading into the fight.

"Fight fans are... going to see a lot of fireworks. If he knocks me down, I'm going to get up and knock him down. I know he'll try to do the same if I knock him down. The main thing is to stay focused and disciplined."

Joshua was dropped to the canvas four times in the June bout and Ruiz, who has never been knocked out in his career, said that he would look to control the fight and use his speed against his taller opponent.

"I want to impose myself in this fight, but I don't want to overlook him," Ruiz added. "He's still a dangerous fighter. I respect him and all the fighters who risk their lives inside the ring... He's going to have some tricks up his sleeve and it's my job to not let that affect me. The main thing is pressure, throw combinations and use my speed. I can't let him grow balls in there."