MEDINAH, Ill. — Tiger Woods was walking with his pro-am playing partners Wednesday at Medinah Country Club when he heard that Serena Williams had pulled out of a tournament in Ohio because of back spasms. It was the second time in the span of three days that she was forced to drop out of a competition. The same injury also forced Williams to retire during the first set of the Rogers Cup final in Toronto.

Woods could relate. He withdrew before the second round of last week’s FedEx Cup playoff opener at Liberty National Golf Club when he awoke after an opening four-over 75 bothered by a strained oblique muscle that left his surgically repaired back feeling stiff. Five days later, Woods said he felt much better, but as a precautionary measure, he refrained from hitting full shots during the second nine of his pro-am before the BMW Championship, which starts Thursday.

Woods, 43, and Williams, 37, are both transplanted Southern Californians who live roughly 25 miles apart in South Florida, but their bond is more than roots-deep. They are trailblazing, transformative champions who, after being the faces of their respective sports for the past two decades, find themselves fighting battles on multiple fronts, against age, injuries and youthful adversaries, all while juggling parental responsibilities.

“That’s why we’ve become so close,” Woods said.

Their journeys from childhood prodigies to parents and single-name icons have taken them down parallel paths. Williams was pregnant with her daughter, Olympia, when she won her 23rd Grand Slam singles title at the 2017 Australian Open to pull within one of the career record-holder, Margaret Court.