Arnold Gjergjaj: The shelf-stacker who is David Haye's next opponent

Arnold Gjergjaj, right, will fight David Haye at London's O2 Arena on Saturday. Andrew Redington/Getty Images

Heavyweight contender David Haye's next opponent is unknown to British fight fans, but he is Switzerland's No.1 boxer.

Critics have dismissed the threat of Arnold Gjergjaj, but the Switzerland-based Kosovo-Albanian has built up an unbeaten 29-fight record, featuring 21 stoppage wins.

Haye (27-2, 25 KOs), a former world champion in two weight divisions, will be by far Gjergjaj's best opponent on what will be just the second time he has fought outside of Switzerland.

Gjergjaj -- nicknamed the Cobra despite a fear of snakes -- still even works weekend shifts in his brother's convenience store and runs his own gym in his home city of Basel.

Gjergjaj, 31, has taken time off from stacking shelves and serving customers on Sundays in the last few months and his trainer Angelo Gallina insists he is ready for the step up in class -- and his highest ever pay day.

"At the moment he's the best boxers we have in Switzerland and the best Swiss heavyweight ever," said Gallina.

"People say he has only boxed in Switzerland, but he can only box where he is getting paid to box and we have made sure he has trained with some of the best fighters in the world like the Klitschkos, Tyson Fury, Robert Helenius and Kubrat Pulev."

Gjergjaj moved to Switzerland aged 14 from war-torn Kosovo. The Kosovo-Albanian was the youngest of seven siblings growing up in Gjakova, a small rural village in Kosovo, and life was very different to what it is now in the pleasant Swiss city of Basel.

"It seems to me that I have lived two lives, one before and one after the war," said Gjergjaj, who trained as a heating engineer after leaving school.

Gjergjaj's best win so far came last year when he climbed off the canvas to beat Russian Denis Bakhtov -- previously destroyed in two rounds by Briton Anthony Joshua -- unanimously on points over 12 rounds. Gallina claims Gjergjaj broke his hand in the fourth round and he is currently ranked 18 in the world by the WBC governing body.