Irwin: United won't stop at 19 titles
The Irishman, who played 529 matches during a 12-year spell at Old Trafford, believes United will face stiff competition when it comes to retaining their crown, touting as many as five teams to feature in the race.
Sir Alex Ferguson's side won an English record 19th top flight title in 2010/11, having finally taken the place of arch-rivals Liverpool in the record books.
“It’s a huge milestone but we won’t be stopping there,” the former full-back said on Manchester United's official website.
“Every year’s a new challenge. Manchester City have got stronger in the last few years, Liverpool have had a quiet time recently but they’ve acquired some good players.
"And of course Chelsea and Arsenal will be in it, too. There’s a challenge to win a 20th title next year.”