David Beckham says he believes in Jose Mourinho despite Manchester United continuing to struggle in their quest to reach the heights of Alex Ferguson's reign.

The former England captain feels United's slump since their iconic manager's retirement in 2013 was to be expected.

But Beckham hopes Mourinho – the club's third manager since Ferguson - will be the man to take United back to the top, despite them sitting sixth in the Premier League.

"It was always going to happen," Beckham said of United's slump at a Q&A session in Johannesburg at the Discovery Leadership Summit.

"We have had a tough few years, but we have had a pretty good 20 years. I believe in Jose Mourinho."

Beckham was even asked if he would contemplate coming out of retirement to play for United again and explained why Ferguson's strict managerial style suited him.

He continued: "We knew if we hadn't played well, the first person who would be waiting for you in the tunnel would be Sir Alex Ferguson. There was a fear factor, but it was a good fear.

"You know what? I'm 41. I would crawl back to Manchester to play there again. But obviously it's not realistic."

While he reflected fondly on his club career, Beckham said his proudest moment was becoming England captain and biggest regret was failing to win anything with the national side.

He added: "Having the beautiful family that I do [is my most special achievement].

"In my career, the one that makes me proudest was being captain of my country. Being given the captain's armband by Peter Taylor, that was my personal proudest moment. 

"To be able to lead your team, your players, your nation out into the World Cup finals, that doesn't get much better.

"I'm a very proud Englishman. I was captain of my country for six years.

"I wasn't what you'd say was a natural leader. But what I did was work hard and thankfully I had team-mates around me that actually followed the lead. That was the way I led.

"To not win anything with England [is my biggest regret]."