Wayne Rooney has identified a simple structural shift as the decisive factor behind Manchester United’s recent improvement: a compact four-man unit protecting the back line.

Rooney, speaking on his self-titled BBC podcast, pointed to the quartet of Harry Maguire, Lisandro Martínez, Kobbie Mainoo and Casemiro as “the main change” driving better results. He highlighted a renewed resilience and collective work-rate as evidence the team were operating with a clearer plan. “Resilient, [a] lot more running than we’ve seen of them under the previous manager … and it looked like they had a plan. Amad was brilliant again [against Fulham], and [Diogo] Dalot as well,” he said.

The move followed a selection shift by Michael Carrick, who restored Mainoo to the central midfield and paired him with Casemiro while Bruno Fernandes has been used further forward. Rooney added: “But I think the main changes for Manchester United are having Harry Maguire and Martínez, and Casemiro and Kobbie Mainoo in front of [them]. Obviously, we can talk about Bruno, he’s United’s best player. But I think having that box of those four has been crucial.”

Tactical context has helped explain why the quartet only recently featured together. Under Amorim the best two centre backs seldom started at the same time. When Maguire returned to the side against Manchester City it was his first start alongside Martínez in a conventional back four since September 2024 under Erik ten Hag. Amorim had also preferred a Casemiro-Fernandes midfield partnership earlier, which pushed Mainoo to the fringes.

The configuration Rooney praises may not be durable. Casemiro’s summer departure at the end of his contract has been announced; the 33-year-old will bid farewell to supporters in May after confirming he will not sign a new deal. Maguire is also out of contract this coming summer and has not yet agreed new terms, leaving his long-term status uncertain.

Chelsea have confirmed the return of Mamadou Sarr from his loan spell at Strasbourg as the club respond to a request from manager Rosenior for an additional centre back.

The 20-year-old Senegal international has completed his move back to Chelsea and is expected to play a significant role under Rosenior. Sarr worked regularly with Rosenior during their time at Strasbourg; he was named captain by Rosenior during the first half of this season despite being on loan.

The search for defensive cover had briefly included Rennes’ Jérémy Jacquet, but Jacquet was unavailable before opting to join Liverpool. Chelsea then turned to a solution closer to home. Aarón Anselmino was controversially recalled from a loan with Borussia Dortmund but, rather than remain with Chelsea, the Argentine has been sent to Strasbourg in place of Sarr.

Sarr is described as a modern-day defender, combining mobility and technical proficiency with a clear understanding of Rosenior’s methods and tactics. That familiarity should ease his transition back to Stamford Bridge and into Rosenior’s plans.

Chelsea have been without the specific central centre back profile since Levi Colwill’s injury during the summer, and Sarr is comfortable in the fabled central centre back role. He can also operate on either the right or left of a back three if required, providing tactical flexibility.

The club’s decision to recall Sarr and send Anselmino to Strasbourg effectively swaps two loaned players between Chelsea and Strasbourg, reshaping the short-term defensive options available to Rosenior. With Sarr returning to the squad, Chelsea add a young, trusted option who already understands the manager’s expectations and is ready to be integrated into matchday selections.

Arsenal were reported to have considered Sandro Tonali on Deadline Day as they sought short-term midfield cover following confirmation of Mikel Merino’s foot injury. The suggestion that Tonali had been offered to Arsenal was strongly denied by the player’s agent, while the club continued to evaluate options.

The need for reinforcements followed Arsenal’s announcement about the severity of Merino’s injury, which leaves the squad down a midfielder for the coming months. Mikel Arteta acknowledged the situation ahead of the Carabao Cup semi-final against Chelsea and confirmed the club were searching the market.

Sky Germany reporter Florian Plettenberg claimed Arsenal were “exploring” a deal for Tonali after an initial approach was rejected. That report was contested by The Athletic ’s well-connected David Ornstein, who said no discussions between the two clubs had taken place and traced the interest back to Tonali’s agent, Giuseppe Riso.

Andrea Berta was described as an “admirer” of Tonali, but the practicalities of completing a transfer so late in the window prevented any move from progressing. In response to The Athletic’s account, Riso told Sky Italia: “Newcastle won’t let Sandro leave in January. We haven’t spoken to Arsenal about this opportunity.”

Arteta addressed the club’s response to Merino’s absence directly. “The news of Mikel was very unexpected, obviously, especially for such a long time,” he said. “So we are actively looking at options and we will continue to do that. My day will be the same as usual, I will be busier and if we have a final solution, I will try to do it, and if we don’t, we will continue in the manner that we are now.

“You need to look and we need to do everything that we possibly can to see if we have a player that is available. If we don’t, we keep what we have,” he added, later conceding he “isn’t relaxed” about the situation.

On the injury itself Arteta was cautious: “It’s a very rare injury, so we have to wait and see once we have the surgery,” the Arsenal boss sighed. “How it reacts daily, monitor it throughout the week. I know Mikel is going to do absolutely everything that he possibly can to come back as quick as possible.”