With an ace out wide, another ace out wide, and then a service winner, Serena Williams booked a place for her and her partner, rising star Victoria Mboko, in the Queen’s women’s doubles quarterfinals.The greatest server in the history of women’s tennis and one of the greatest players of the modern era is back, with a comfortable 7-6(2), 6-2 win over No. 3 seeds Erin Routliffe and Nicole Melichar-Martinez marking her return to tennis after almost four years away.There was some uncertainty about how Williams, 44, would take to the match court. Over 90 minutes of play Tuesday evening in west London, there was plenty of brilliance, plenty of rust, and plenty of evidence that Williams had made an outstanding choice of partner. Mboko, the 19-year-old Canadian and world No. 9 in singles, produced a superb performance, and Williams described her as “holding up the team” in their post-match interview.Routliffe and Melichar-Martinez seemed a little overawed by the occasion, both hitting costly double faults and missing regulation volleys. They were playing together for the first time and, despite being accomplished doubles players, they lacked chemistry and cohesion. In that context, it was impressive how quickly Williams and Mboko, also a scratch pair, could gel.During the first set, Williams appeared a little nervous and tentative on a few shots. In the first game, she missed a makeable volley before settling and hitting a couple of good ones to help Mboko hold serve.In Williams’ first service game, she unleashed a couple of unreturned first serves to extend her and Mboko’s lead to 3-0. The serve is such an interesting part of Williams’ comeback — even if she’s not as quick around the court as she used to be, she will still be competitive if it’s anything like as potent as it was in her prime. The signs on Tuesday were encouraging, as it sped up from under 100 miles per hour at the start to as high as 120 mph toward the end of the first set.It was also clear only a few games in that Williams was taking this extremely seriously. She had said in a news conference before the match that she had nothing to lose on her return and that “everything is just a gain,” but that shouldn’t be mistaken for thinking she will be anything other than uber-competitive.With Mboko serving at 3-1, Williams screamed in anguish after missing a shot and then apologized earnestly to her partner. Williams then roared with delight after putting away an easy volley.