The Red Devils legend has hailed the Scottish manager\'s abilities to fend off the challenge from the newly-rich local rivals Manchester City as the club aim for a 20th championship.Sir Bobby Charlton has commended the work Manchester United manager Sir Alex Ferguson during his 25-year period at the club, claiming he has been central to the club\'s title challenge this season.The Scottish manager has had to pit his wits against the extreme wealth of rivals Manchester City, but the former Red Devils\' midfielder feels the services of the “marvellous” Sir Alex are priceless.Charlton admitted that a lot of credit has to go to the manager for this season\'s efforts but also conceded that he has run out of superlatives to describe the man who has won 37 trophies during his time at the club.\"So much credit has to go to Alex and his coaches for having United involved in the title race again this season,\" Charlton told United Review.\"At the start of every campaign you want to avoid injuries and suspensions, and United have had such incredible misfortune with injuries that it\'s really staggering to be in the position we\'re in.\"There\'s been so much said about Alex - especially this season, with him passing his 25th anniversary with the club - that it\'s hard to add anything new. He\'s just marvellous, and the way he lifts everyone around him is incredible.\"The best example of that is in the reaction to City\'s 6-1 win at Old Trafford earlier this season. It shocked everybody associated with the club and it\'s certainly something you hope will never happen again.\"There\'s a part of you that would like to set the record straight with a similar win one day. But to come back from that result so strongly speaks volumes for how influential he is.\"The season\'s title race draws many comparisons to the last time Manchester City won the league in 1968, a year in which Charlton was playing.Although he admitted the pain of losing to their rivals was hard to take, he claimed that winning the European Cup in the same season eased his woes.\"City hadn\'t won the league for a long time and they were so keen to win it back,\" he remembered.\"They performed really well to take the title from us on the final day of the season, and I have to say they deserved to win it. It really was a great performance.\"I remember, though, going to a function with Mike Summerbee a few days after we\'d won the European Cup at Wembley – three weeks after City had won the league - and Mike was half-laughing when he said: \'You always find a way to beat us, don\'t you?\'\"The European Cup was the most important trophy you could win, and it meant so much for us to win it that it was all anybody was talking about. Unfortunately for City, it overshadowed their achievement so soon after they\'d done it.\"