Javier Hernandez says Alex Ferguson's exit was 'very difficult'

Javier Hernandez says he is not surprised by Manchester United's lack of Premier League success in recent years, as the Mexican prepares to face his former club this weekend.

The 29-year-old joined West Ham from Bayer Leverkusen this summer, two years after he left United for the Bundesliga side.

The luck of the Premier League fixture list means he is set to make his Hammers debut at Old Trafford on Sunday.

Hernandez won two Premier League titles during his time at United, the second of which came in 2013 as Sir Alex Ferguson retired in style by delivering another trophy for the club.

Since Ferguson left his post, United have had four managers; David Moyes, Ryan Giggs, Louis van Gaal and now Jose Mourinho.

But that success of 2013 remains the last time the Red Devils won the league and they have finished outside the top four in three of the past four seasons.

That does not come as a surprise to Hernandez, however, as the Mexico international always felt Ferguson's departure would have a knock-on effect.

"The change of Sir Alex retiring, we knew it was going to be very difficult. He was unique in [the] history of football," he said.

"We all knew there was going to be a transition.

"You cannot have a manager for 26 years - the best manager in history, achieving everything, changing the squad every couple of years, changing players, even all the staff sometimes, there was always going to be a transition.

"I wasn't surprised. It was normal. Nobody expected when we played for David Moyes that we wouldn't be in European football. But that is part of football."

Hernandez, who hit 59 goals for United after being signed as a relative unknown from home-town club Guadalajara in 2010, concedes Ferguson gave him plenty of life lessons that he has carried with him ever since.

"He told me a lot. He was a manager who liked to stay in contact with his players," he said.

"The one piece of advice I remember when I came was to keep going and doing what I was doing in the national team for the club and to keep that confidence.

"He liked me and that is why he brought me to Manchester United.

"I didn't see it [his retirement] coming. Nobody did. It was very strange. We were shocked but we were very respectful too because he decided squads, games, everything - it was his life."