Bayern Munich coach Pep Guardiola has warned that Manchester United's goodwill towards manager David Moyes will not last forever.
The Scot has come under fire at United after taking last season's title-winning squad to seventh in the table this term.
Speaking ahead of the two sides' meeting in the Champions League on Tuesday, Guardiola has claimed that Moyes must win trophies if he is to keep his position at Old Trafford.
He told reporters: "In the big clubs when you don't win, you are always in trouble. You have to look forward and win games. Here, in Spain, in Italy, you have to win at the big clubs.
"Manchester United, in the last 10 to 15 years, dominated the Premier League and Europe too, arriving in many finals.
"In the big clubs that happens. It happened with Bayern - last year we won everything and you have to try to maintain that level and so far we did it, at least in the league."
Moyes's side have lost 10 games this season - the most that they have ever suffered in a Premier League campaign - while Bayern were recently crowned Bundesliga champions for the second successive year.
