Sir Alex Ferguson managed Manchester United between 1986 and 2013, winning 38 trophies during a hugely successful period, including 13 Premier League titles, five FA Cups and two Champions League crowns.

Ferguson stood down as head coach after leading the club to their 20th league title, and it would be fair to say that the English giants have found it difficult to come to terms with life without the Scot at the helm.

The 78-year-old, who announced his retirement seven years ago to this very day, will forever be remembered as one of the best managers in the history of the game, but there is no question that he also had some of the best players in world football over the course of his 27 years in charge.

Here, Sports Mole has put together a list of who we believe to be Ferguson's 10 greatest signings from his time as head coach.

10. Patrice Evra: £5.5m from Monaco

United signed Evra from Monaco in January 2006, and it would be fair to say that the Frenchman proved to be a wonderful player for the club. The left-back initially had problems adapting to the English game, namely being substituted at the interval of his Premier League debut away to bitter rivals Manchester City.

Evra was to prove his class in the coming years, though, making 379 appearances in all competitions, contributing 10 goals and 40 assists in the process. The full-back won five Premier League titles, three League Cups and the Champions League during his time at Old Trafford.

His consistency in terms of appearances and performances made him a favourite of the United fans, and the deal, which is believed to have cost the Red Devils in the region of £5.5m, must go down as one of the biggest bargains in Premier League history considering the quality and leadership he provided.

9. Dennis Irwin: £625,000 from Oldham Athletic

Another left-back is ninth on the list, and there is no question that Irwin deserves his spot in the selection. The Irishman joined the Red Devils from Oldham in 1990 for £625,000 and went on to make 529 appearances for the club, winning seven Premier League titles, two FA Cups and the Champions League, amongst other trophies.

He was named in the 1998-99 Premier League Team of the Season and like Evra, showed incredible consistency in terms of staying free from injury and providing a particular level of performance.

There were certainly more glamorous arrivals during Ferguson's time as head coach but perhaps few more important than Irwin, who has to be considered as one of the most under-rated left-backs of all time.

8. Rio Ferdinand: £30m from Leeds United

Ferdinand became the most expensive British footballer in history when he moved to Old Trafford from Leeds United in July 2002. It was a considerable investment from United at the time, but it would be fair to say that the now 41-year-old proved to be a wonderful signing for the Red Devils.

Arguably England's best centre-back in the Premier League era alongside John Terry, Ferdinand made 455 appearances for the club before leaving at the end of the 2013-14 campaign.

The former West Ham United youngster won six Premier League titles during his time at Old Trafford, in addition to lifting the 2007-08 Champions League. He is the joint-most expensive player on this list but simply has to be included when discussing Ferguson's greatest signings as head coach.

7. Nemanja Vidic: £7m from Spartak Moscow

Ferdinand's partner in crime, Vidic is also deserving of a spot in this particular list. Like Evra, the Serbian struggled on his debut against Manchester City, but he went on to become one of the best centre-backs in world football during his eight years at Old Trafford.

Vidic captained the Red Devils from the start of the 2010-11 campaign and made 300 appearances for the English giants in all competitions, contributing 21 goals in the process.

The former centre-back won five Premier League titles, three League Cups and the Champions League under Ferguson, and the fact that he cost just £7m is huge credit to the club. Indeed, a player of Vidic's ability and leadership skills in the current market would likely cost upwards of £80m.

6. Steve Bruce: £825,000 from Norwich City

Bruce joined United from Norwich City in 1987 and went on to make 414 appearances for the club, winning 12 trophies, including three Premier League titles, three FA Cups and the European Cup Winners' Cup.

The former centre-back actually became the first English player of the 20th century to skipper a side to the double, and he formed a hugely successful partnership with Gary Pallister at the back. Incredibly, Bruce was never selected to play for England but will be remembered as one of Ferguson's best ever signings.

There is no question that the now Newcastle United boss played a leading role in Ferguson's early success at Old Trafford, and it is fitting that he won his third Premier League title in 1995-96 before leaving.

5. Wayne Rooney: £30m from Everton

United won the race to sign a teenage Rooney from Everton in the 2004 summer transfer window, and he went on to become the club's all-time leading goalscorer, enjoying huge success in the process.

Rooney scored 253 goals in 559 appearances for the 20-time English champions and played a leading role in the team's success, winning five Premier League titles, one FA Cup and the Champions League.

The former England captain was named in the PFA Premier League Team of the Year on three separate occasions under Ferguson, and although the pair had a difficult relationship at times, there is no question that they needed each other in their respective careers.

4. Roy Keane: £3.75m from Nottingham Forest

An absolute certainty for this list, Keane was nothing short of inspirational for United. He arrived from Forest ahead of the 1993-94 campaign and went on to make 480 appearances for the English giants in all competitions, contributing 51 goals from central midfield.

Keane won seven Premier League titles, four FA Cups and the Champions League during his time at Old Trafford, captaining the team from 1997, taking over from a certain Eric Cantona.

The former midfielder played a key role in United's dominance in the 1990s and early 2000s and although he left under a cloud, the Irishman will forever be remembered as one of the club's most important players.

3. Eric Cantona: £1.2m from Leeds United

Cantona controversially joined United from Leeds for £1.2m in November 1992, and the Frenchman was to spend five years at Old Trafford, making 185 appearances in all competitions.

The famous number seven scored 82 times for the Red Devils, including 25 during the team's 1993-94 double-winning campaign but his contribution cannot be explained in statistics alone.

Indeed, Cantona's aura and presence helped United win again, becoming a talismanic figure in a relatively short space of time. The now 53-year-old certainly had some disciplinary problems at Old Trafford, but Ferguson's trophy cabinet would perhaps be less crowded had Cantona not arrived.

2. Cristiano Ronaldo: £12.25m from Sporting Lisbon

Alongside Lionel Messi, Diego Maradona and Pele, there is an argument that Ronaldo is the greatest player in the history of the game. He arrived at Old Trafford as an 18-year-old in 2003, having impressed a number of United players with his performance in a pre-season friendly for Sporting Lisbon.

The Portuguese was moulded into a world-class superstar by Ferguson, ultimately scoring 118 times in 292 appearances for the Red Devils before leaving for Real Madrid in the summer of 2009.

Ronaldo won three Premier League titles, one FA Cup and the Champions League during his time in English football, but Madrid proved to be too much to resist when they came calling. A number of clubs were thought to be interested in the forward at the time of United's purchase and therefore he must be considered as one of Ferguson's greatest signings.

1. Peter Schmeichel: £550,000 from Brondby

Ferguson once called the £550,000 deal that brought Schmeichel to Old Trafford "the bargain of the century". Arguably the greatest goalkeeper in Premier League history, the Dane was another hugely inspirational figure for the Red Devils during his eight years at the club.

Indeed, the now 56-year-old made just shy of 400 appearances for United, winning five Premier League titles, three FA Cups and the Champions League. Every great side has a solid base, and Schmeichel's contribution to the cause cannot be downplayed. Indeed, he was vital to the team's success in the 1998-99 campaign, famously saving a Dennis Bergkamp penalty in the final minutes of the FA Cup semi-final, before skippering the side to European glory due to Keane's suspension.

This particular list is incredibly competitive but when taking into account value for money and overall contribution, it is very, very difficult to look past Schmeichel, particularly when goalkeepers are judged differently to outfield players.