Things haven't been easy for Manchester United as of late. The Red Devils went into Sunday's clash with West Ham having lost three of their last four games in all competitions, a run that has seen them fall well behind the pace in the Women's Super League title race and weakened their incredibly strong position in the Champions League, ahead of two very tough final games in the league phase, starting with the hosting of eight-time winners Lyon on Wednesday. The return of Phallon Tullis-Joyce, then, could not have been better timed.It is no coincidence that in three games without the United States international, since she suffered a fractured eye socket at the start of November, United conceded nine goals. Compare that to the team's first 14 games of the season, prior to her absence, when they conceded just seven times. That's no slight on Safia Middleton-Patel, the young academy product who took her place for those three games and impressed at times, particularly given her inexperience. But to expect her to perform to Tullis-Joyce's level at this stage of her career would've been unfair, especially considering she has played limited minutes with those in the defence in front of her, too.Now, though, the 29-year-old is back, giving United a much-needed boost ahead of a huge end to 2025. Tullis-Joyce wasn't at her busiest as the Red Devils got a necessary win at home to West Ham on Sunday, against a side second-from-bottom in the WSL standings. But she may be over the next week or so as United bid to sign off for the winter break in a successful manner, with qualification for the Champions League knockout stages a huge part of that.While Tullis-Joyce didn't have a lot to do on Sunday, bar picking the ball out of the back of her net after Shekiera Martinez's remarkable overhead kick, her presence did feel impactful. The Hammers registered just 14 shot-creating actions in the game, the lowest by any of United's opponents since a 4-1 win over Everton back in mid-October, and had an expected goals statistic of 0.6, also the lowest United have allowed since victory over the Toffees. With Tullis-Joyce back between the sticks, it felt like there was more familiarity and, as such, assuredness in the United defence. Those in front of the goalkeeper did an excellent job of stifling the lively Martinez and limiting West Ham, and the shot-stopper herself did what was necessary when called upon. It wasn't a headline-grabbing return but that also felt important, as the American adapts to wearing a mask as she continues to recover from her injury.Again, none of that should reflect as criticism of Middleton-Patel, the 21-year-old who deputised for Tullis-Joyce during her three-game absence. It said a lot about the Wales international, in fact, that head coach Marc Skinner chose her over Kayla Rendell, who has the actual No.1 shirt on the United books, made 134 senior appearances during her six years with Southampton and has won England call-ups in recent times.Middleton-Patel's performance against Paris Saint-Germain, just her second-ever appearance for the Red Devils, was particularly impressive, with her not daunted by the Old Trafford stage of the magnitude of playing in such an important Champions League fixture. Skinner called her "excellent" after that 2-1 win, noting how well she had "acquitted herself and come into the team" under the circumstances.But it's never easy when a team has to change goalkeepers, especially moving from one with quite a lot of experience to one with much less, and that would become apparent over the course of the next couple of games. Middleton-Patel endured some tough moments in the losses to Manchester City and Wolfsburg, games which will hopefully prove to be valuable learning curves as her career evolves rather than anything else.United's defence as a unit was guilty of costly errors, too, something unlikely to have been helped by the absence of the reliability and familiarity of Tullis-Joyce. Combine that with the changes already needed at the back due to an injury to central defender Millie Turner, whose time on the sidelines has had a double impact on the spine of the team because it is holding midfielder Dominique Janssen that has filled her spot, and United have not looked like their usually solid selves in recent weeks.Those struggles have only served to highlight the lack of depth in this squad, caused only by the club's own inactivity in the window, and the fatigue that small squad is feeling harder as it competes in the Champions League proper for the first time.Tullis-Joyce's return certainly can't resolve the latter issues, with Skinner again making sure to emphasise that he needs signings in the January window after Sunday's win, but she does have the match-winning qualities to bail out defenders when they make mistakes or produce the sort of world-class save that few shot-stoppers can, to earn her side points almost single-handedly in moments.In the WSL and Champions League proper this term, the expected goals against statistic calculates that Tullis-Joyce should have conceded 11.9 goals, but she has only picked the ball out of the back of her net on seven occasions. That makes for an incredibly impressive positive differential of 4.9 goals prevented across her 11 appearances.That quality wasn't called upon often on Sunday, as she made her first appearance in a month, but it is likely to be before United hit the winter break. On Wednesday, the Red Devils host Lyon, the eight-time European champions who look like one of the biggest contenders, if not the biggest contender, for the Champions League trophy again this year.OL are the third-highest scorers across Europe's top five leagues and the Champions League so far this season, only behind Barcelona and Wolfsburg, and are still unbeaten, winning 12 of their 13 games played. The only blip on that record came in a thrilling 3-3 draw with Juventus, United's sixth and final Champions League league-phase opponent.Skinner's side will travel to Turin in a week's time, after taking on a very good Tottenham team this coming weekend. Under the charge of former United assistant Martin Ho, Spurs have been the surprise package of the WSL season so far, sitting fifth in the standings, level on points with reigning European champions Arsenal, after 10 games.Wednesday marks the start of a huge week for United then, who find themselves seven points off the pace in the WSL title race after their recent blip in form, but still in a strong position to reach the next round of the Champions League, only outside the top four places on goal difference. That said, it can be argued that they have the hardest final two fixtures of the league phase of any team in the top six, with there no time to rest on their laurels.Sunday's win was vital to raise the confidence in a group that has seen it dented this past month, and Tullis-Joyce's return may prove to be even more important as these final three games of 2025 unfold. To compete for trophies and in the biggest competitions, a team needs to have game-changing stars, players who can deliver defining moments. In the American, the Red Devils have exactly that, with the stage set for her to prove as much over the course of the next week.