Manchester United’s struggling attack has been laid bare in the past two games, with Louis van Gaal’s side being shutout against both Manchester City in a tedious derby and then against Middlesbrough when being sent crashing out of the Capital One Cup. Nearly 16 months after taking charge, Van Gaal has certainly improved the side following the decline under David Moyes, but attacking inspiration remains conspicuous by its absence.

With Memphis Depay failing to deliver on his undoubted potential to such an extent that he is already out of the side and Wayne Rooney continuing to haul his fatigued body around in vain, only teenager Anthony Martial is currently offering any verve at the front end of the team. While much of the struggles can be ascribed to Van Gaal’s stiflingly regimented tactics, there is also a dynamic star quality lacking, especially for one of the richest clubs in the world.

That has not been for a lack of trying in the transfer market in recent times. In a change of strategy, Manchester United have attempted to join the ranks of the galactico-hungry by pursuing some of the world’s big-name players. To date, though, they have been frustrated.

Two of those they have expressed a strong interest in remain at Real Madrid, and, according to recent comments from one prominent member of the club, will do so for the foreseeable future. Cristiano Ronaldo has long been targeted for a return to the club he left in a then-record transfer in 2009. With his contract set to enter its final two years next summer, there has been much speculation once again that the 30-year-old could be tempted by a move back to a club where he is already a legend.

Yet Ronaldo insisted again only recently that he was intent on retiring at Real Madrid. And now former France star Zinedine Zidane, currently coach of Real Madrid’s Castilla, or B, team has insisted he sees no reason why the three-time Ballon d’Or winner would leave.

“Big players are what people want to read about, so that is why they are written about, but why would Real Madrid have any intention of selling the best player in the world?” he told British magazine ShortList. “No he is not for sale, it wouldn’t make sense.”

Zidane also discussed the future of another long-time Manchester United target, Gareth Bale. The presence of Ronaldo, and the Welshman’s struggle to impose himself on the team, has regularly been cited as a reason why Bale may be tempted by a return to the Premier League, despite breaking Ronaldo’s transfer fee record when leaving Tottenham in 2013.

Bale and Real Madrid have always denied that there was any chance of that prospect transpiring anytime soon, and Zidane has offered up the same message.

“Of course clubs are going to want Gareth, he is one of the best in the world, but I am not sure how much clearer we can be,” he said. “Gareth has made it clear, his agent has made it clear, we have made it clear, his future is at Real Madrid. We sign the best players in the world, we don’t sell them.”

Currently, Manchester United’s best prospects of landing one of the stars in La Liga may rest with Barcelona’s Neymar. There were reportedly encouraging signs provided to United from the Brazilian’s camp this summer over a potential move. In his third season at the Camp Nou, Neymar is entering a crucial period with his contract having less than three years to run and Barcelona eager to renew it. There have been suggestions that he could be tempted to leave Barcelona in order to get out of Lionel Messi’s shadow and enhance his chances of being voted the world’s best player. United would be one of the few clubs who could offer him the stage to do that and afford him.

Speaking this week, former Barcelona president Joan Laporta speculated that the club may need to sell a player of Neymar’s stature in order to balance the books. But the man currently in the president’s chair, Josep Maria Bartomeu, has stressed he remains confident of the 23-year-old extending his current deal.

“He has a contract until 2018, we will be discreet and announce [the new deal] when it’s done,” he said, according to Barcelona-based daily Sport.

A report in Sun claims that Barcelona are ready to double Neymar's salary to £500,000 a week to make him the world's third-highest paid player, behind Ronaldo and Lionel Messi.