Anthony Joshua is focusing on the quality of his mindset and his approach to sparring before his heavyweight world title rematch with Oleksandr Usyk. Joshua is expected to face Usyk later this year for the unified WBA, WBO and IBF belts, after losing them to the Ukrainian. He lost the belts in London last September. The Ukrainian, who was also the first undisputed champion at cruiserweight, defied the odds to win the belts in comfortable fashion from Joshua in front of over 63,000 of his home fans at the Tottenham Hotspur stadium. “Let’s focus on quality,” Joshua said in an interview with Sky …