'There will be arguments' - Wayne Rooney gives verdict on Pep Guardiola vs Sir Alex Ferguson debate

Manchester United legend Wayne Rooney has the utmost respect for Pep Guardiola's achievements but believes Sir Alex Ferguson is the greatest manager of all time.

Manchester City became the first team to win four successive Premier League titles this season, a year after they won the treble by lifting the Champions League.

However, the 115 charges hanging over City have left a dark cloud over their success and some have questioned their sporting achievement as the uncertainty rumbles on.

Nonetheless, Guardiola is widely regarded as the most successful coach of his era and is included in the conversation on who is the greatest manager of all time.

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United had not won a league title for 19 years when Ferguson was appointed, but an unprecedented era of dominance followed and the Scot retired having won 13 league titles.

Before arriving in Manchester, Ferguson won three Scottish titles with Aberdeen and led them to victory against Real Madrid in the 1983 European Cup Winners' Cup.

Rooney believes that gives him an edge over Guardiola. "I think of course there are going to be arguments as to who is better, but I think people tend to just look at what Sir Alex did at Manchester United, and what he did at Aberdeen was incredible," he told ESPN Brazil.

"And you'd ask the question, could Guardiola do that at a team like Aberdeen? There's questions, there's debate, I think Guardiola for his era is of course the best and he's changed the way football is played worldwide... but yeah, for me Sir Alex, what he achieved in the game is incredible."

In February, Rooney was sacked as