Now, ahead of the first rematch of his career, Parker is determined to make the most important change of all and turn a controversial result into a convincing victory.
The 29-year-old needs to make a statement to remain relevant in the heavyweight division and, after a "tremendous" training camp in Morecambe, Parker is confident his partnership with Lee will produce exactly that.
The quest for additional power saw Parker (29-2) tip the scales at a career-high 114kg at today's weigh in, with Chisora (32-11) coming in slightly lighter than May's bout at 113kg.
Fighting a rematch for the first time provides Parker an ideal opportunity to showcase the alterations he has since made, knowing the one thing he has to change most.
"It's given me time to work on things that didn't go so well in the first fight," he said. "I don't want to get to the end and then question whether I won or not. I want a convincing performance."