<p>After nearly four years ‌away, the 44-year-old American great partnered Canadian teenager ‌Mboko to victory against ⁠Nicole ‌Melichar-Martinez and Erin Routliffe in ​front of a sell-out crowd on Tuesday.</p><p>They ​were scheduled to play Canada's Leylah Fernandez and ⁠Germany's ​Laura Siegemund in the quarter-final, but 19-year-old Mboko has been forced to withdraw ‌after slipping painfully during her singles match against Czech Republic's Karolina Pliskova on Wednesday.</p><p>Mboko had to retire from that match and left the court hobbling and close to ‌tears.</p><p>Williams, who has won ​23 Grand Slam singles ‌titles, will continue her comeback in Berlin next week and could seek a wildcard for the ⁠Wimbledon ⁠championships.</p>