Queen’s Club, LONDON — Nearly four years after playing what appeared to be the final match of her career, Serena Williams is back on a professional tennis court.Williams, 44, stepped onto the grass at Queen’s in west London last week and over the weekend, before a wild card appearance in the women’s doubles alongside 19-year-old Canadian Victoria Mboko.Her return follows months of waiting, after she re-entered tennis’ anti-doping testing program late last year and became eligible to compete in February.The attention surrounding Williams’ return at the prestigious tournament was evident long before she stepped onto the match court. During practice sessions at Queen’s, spectators packed the viewing areas several rows deep, lining the railings and spilling down the walkways to watch Williams and Mboko train, with phones raised throughout.After Williams’ first appearance on the practice courts Thursday, the 23-time singles Grand Slam champion’s next run-out arrived Sunday.Williams and Mboko were scheduled to practice on Court 7 Saturday morning, but a day of rain, which eventually saw all qualifying matches abandoned, prevented that. Williams instead practiced off-site, and posted a clip on TikTok from a nearby indoor court at a separate club. “When it rains, we adjust,” she wrote.With Sunday’s practice set for 10 a.m. on Court 7, the closest court to the private members’ clubhouse, Williams emerged with a quick change into white tennis shoes with a black Nike tick, along with some custom ankle straps and the black face patches she wears to relieve sinus pressure. She started the one-and-a-half-hour slot by hitting some rallies with Mboko from behind the baseline, under the guidance of Australian coach Rennae Stubbs.Media cameras pointed down from the hospitality balcony on Williams like a spotlight, following her every move of the session. It ended in a 30-minute practice set with Mboko, against two male training partners.