One of the worst-kept secrets in football was let out last week when, at a Marouane Fellaini press conference, Manchester United boss David Moyes revealed that the club wanted to sign Everton defender Leighton Baines in the summer.

Moyes faced criticism for paying £27.5m for Fellaini when the deal could have been done for £4m less in July, but the Scot claimed that the delay in the transfer was due to the Premier League champions' pursuit of Baines.

It is believed that Moyes will return to his former club for the left-back in January, but here Sports Mole offers its view on whether the England international is a necessary signing for the club.

It would be no exaggeration to say that Baines has been one of the best, if not the best left-back in the Premier League over the past couple of seasons. Defensively sound and with an incredible left foot, he has drawn interest from across Europe. However, at the age of 28, he cannot be seen as the long-term solution to United's left-back problems.

It would be fair to say that current United left-back Patrice Evra took some time to settle into life at Old Trafford after joining from Monaco in 2006, but over the last seven years, he has emerged into one of the best full-backs the Premier League has ever seen.

While his attacking talents are not in question, even the most ardent of his supporters would find it difficult to argue that the Frenchman has struggled defensively over the last couple of years. He remains a supreme athlete, but at the age of 32, it is only right that the club are preparing for life after Evra.

What this summer has done to Evra's confidence remains to be seen with the club's open pursuit of Baines and the late attempt to sign Real Madrid full-back Fabio Coentrao on loan. However, for now at least, Evra remains the undisputed first-choice for the English champions.

It is also difficult to ignore Evra's consistency over the last couple of seasons. Since 2009, his record in the league per season reads 38 appearances, 35 appearances, 37 appearances and 34 appearances. For a player who is not afraid to put his foot where it hurts, he has been an incredible servant to United since making his debut in 2006.

Alexander Buttner arrived at United in January to provide competition to the Frenchman, but with the greatest of respect, the Dutchman is not the man to provide a long-term solution. He is a willing worker and indeed a reliable back-up defender, but despite his attitude, which is first class, he does not have the defensive awareness to perform in such a position at the highest level.

There is a player who has the capabilities, however, a player who made his first league start for United since November 2011 when he appeared in Saturday's 2-0 win over Crystal Palace. With his brother Rafael da Silva out with an ankle problem, Fabio da Silva was handed a rare start in Moyes's first league win at Old Trafford.

The 23-year-old's career has stalled somewhat in the last couple of years with a loan spell with Queens Park Rangers last season not going according to plan. While his brother has developed into arguably the best right-back in the Premier League, Fabio is still desperately trying to make his way into the team that he joined in 2008.

When Fabio and Rafael were with Brazilian club Fluminense during their teens, Fabio was seen as the brighter option. He captained the club and indeed his country at youth level and also scored 10 times in 13 games for the Brazilian Under-17s, operating mainly in a wide left position.

He made his debut for United in 2009, making 11 appearances in total during his first full season, and played 25 times in all competitions in the 2010-11 campaign. Former United boss Sir Alex Ferguson's faith in the youngster was demonstrated when he selected Fabio for the 2011 Champions League final against Barcelona in which his side were beaten 3-1.

When Rafael and Fabio arrived in England, they were described as 'Brazil's answer to the Neville (Gary and Phil Neville) brothers'. It has not quite happened for the latter thus far, but there is no question that he has the ability to make the left-back position his own.

Rafael flirted with the first team up until last season when he made 37 appearances in all competitions. Now, he is the undisputed first-choice right-back for the club. With the increasing number of matches throughout the season, Fabio will hope that he can move into double figures as he attempts to take the baton from Evra.

It is not difficult to understand why Moyes is courting a left-back and a player of the calibre of Baines, but the solution to his problem could be provided by a 23-year-old who has the potential and indeed time to make it to the very top.