Dereck Chisora is unmoved by the changes to his opponent as the World Boxing Organization inter­national heavyweight champion prepares to defend his title against Ondrej Pala on Saturday.

The 29-year-old Chisora, who will also be gunning for the vacant World Boxing Association international heavyweight crown at the Copper Box Arena in London, was scheduled to face Arnold Gjerjaj, then Matteo Modugno, before eventually signing to face Pala, of the Czech Republic.

Pala has won 32 of his 35 fights and was drafted in at short notice following a rib injury ruling Modugno out, but Chisora is ready for all-comers.

"You just have to keep going with it and keep pushing," he said. "You can't complain. I have been aiming for the same weight on those scales all the time, so it is no different for me, no different at all.

"First of all they sign the contract, but then they get in the gym and they get hurt. My last opponent pulled out because he got injured; it is not like he didn't want to fight, we are in the fighting game and everyone wants to fight."

Chisora has been determined to lose weight and looked in fine condition during his media workout yesterday.

"Things are looking good. I wanted to lose a bit of weight and I'm walking around feeling good," he said. "I'm on the verge of losing even more weight, so that is good."

Chisora, who has won all three fights since losing to David Haye in July 2012, has backed Haye to return to the ring despite the former WBA heavyweight champion suggesting his career may be over following back surgery. "He will be back," Chisora said. "He will be back because he likes boxing. It is difficult to get away from it if you have the passion."

Chisora's defeat at the hands of Haye was his third in a row after having previously only lost to Tyson Fury in his opening 15 bouts.

Vitali Klitschko also beat Chisora during that time for the vacant World Boxing Council heavyweight title. But success in Saturday's main event at the Copper Box, with the likes of Nathan Cleverly and Frank Buglioni on the undercard, could propel Chisora back in to the title frame against Vitali's brother, Wladimir.

Chisora, though is only interested in the here and now and recording his 19th professional victory.