At the southernmost point of the All England Lawn Tennis Club’s vast grounds, Serena Williams was starting another day of training as the clock ticked down to her first singles match after four years of retirement. Her training partner for the morning, Marta Kostyuk, soon joined her on court 10 in Aorangi Park, the quaint practice area reserved only for players.

Kostyuk is one of the more extroverted players on the tour and she is widely known for speaking her mind under all circumstances, but when Williams greeted Kostyuk and thanked her for the training session, for once the Ukrainian looked at a loss for words: “No, thank you for playing with me,” she responded.

That is the effect of Williams, one of the greatest athletes of all time, whose career has influenced almost every one of the players who have come after her. Between her peerless achievements and her massive profile, she has occupied so much space in the minds of most people involved in tennis for so long and it took some time for the sport to move on after her career wound down. Here she is again.

The news that Williams had taken the last available singles wildcard into the women’s singles draw, which was delivered by the All England Club at about the latest possible moment on Sunday evening, has naturally spawned thousands more questions. After all she has achieved, the motivations around Williams’s comeback remain opaque.

Williams has framed this comeback as an opportunity to share her lifelong profession with her children, Olympia and Adira, and her eldest daughter, Olympia, accompanied Williams during her practice sessions at Queen’s. As with so many great athletes, it is impossible to replicate the emotions and adrenaline that come with battling to the death on court in front of a crowd. So many sportspeople are drawn back in.

There are, of course, other possible motivations. Some point to her usage of the GLP-1 drug Zepbound and her role as the spokesperson for Ro, the company that manufactured it, as a possible reason for her return – the broadcast of her comeback doubles match at Queen’s was sponsored by Ro. Others wonder if she misses the limelight and attention that comes with being a top tennis player. Perhaps she really was just bored.

She has certainly been working hard in the buildup to Wimbledon. Williams has been so visible on the grounds this week that it has actually been difficult to avoid her. In the past she would often book the earliest practice slots, train privately with her hitting partner and then leave the tournament site as early as possible.

This week, however, she has trained with and played practice sets against a selection of other singles players, including Maria Sakkari, Jaqueline Cristian and Kostyuk. Williams looked rough when she played points with Sakkari on Tuesday – she was erratic off the ground and her footwork was sluggish, but on Thursday Williams impressively went toe to toe with Kostyuk, the world No 13, for more than an hour. Although her movement around the ball and out of the corners is still an issue, her serve remains a singular weapon. Towards the end of their practice points, Williams was striking the ball cleanly and teeing off on returns, prompting Kostyuk to smack her racket bag in frustration.

Playing matches, with the added tension, adrenaline and physicality, is a completely different beast to practising. The most pressing question surrounding Williams remains what her level will be on the court, particularly considering how late she left it to take a wildcard. She certainly does not know the answer to this question herself. Williams, however, received a good first round draw against Maya Joint of Australia. Although Joint is a talented young player almost 25 years younger than Williams at 20 years old, she is in the middle of a brutal sophomore slump and has lost 13 of her past 14 matches.

If she were to win, Williams’s first seeded opponent could be the Filipino sensation Alexandra Eala, the 29th seed. Iga Swiatek, the third seed and defending champion, could await in round three. For now, the other rounds are irrelevant. Tennis players often speak of taking things match by match and point by point but, at 44 years old and after being retired for four years, here she cannot afford to do anything else.

This is a curious time for the WTA as a whole. After separating themselves from the field at different points over the past year, the four most noteworthy players – Aryna Sabalenka, Elena Rybakina, Iga Swiatek and Coco Gauff – have been unconvincing.

Gauff is not even ranked inside the top four after losing early in her title defence at Roland Garros and she is at her worst on grass; Sabalenka is enduring her worst run of form since becoming world No 1. Both Rybakina and Swiatek, meanwhile, are just not playing well. Any one of those four could catch fire and shut out the rest of the tour, but as ever this is an open, competitive field, particularly with the added challenge of playing on grass. Mirra Andreeva has not competed since winning her first grand slam title at the French Open but the 19-year-old is already determined to continue adding to her title count.

Deep runs from players such as Karolina Muchova and Belinda Bencic, whose games suit this surface so well, would not be at all surprising, nor would a long-awaited deep run from Jessica Pegula. Amanda Anisimova, last year’s finalist, comes into the tournament in poor form after struggling with injury in recent months and there is some concern over Elina Svitolina, who was forced to withdraw from Bad Homburg on Wednesday due to a hip injury. Much will become clearer over the course of Wimbledon, but for the first few days at least Serena Williams will take up the majority of space in most minds across the All England Club, as has been the case for so much of the past three decades.