Manchester United manager Jose Mourinho has suggested foreign managers are devaluing England's FA Cup by fielding under-strength teams that expose them to the risk of upsets.

Liverpool, Bournemouth, West Bromwich Albion, Stoke City, Watford and Hull City have lost to lower-league teams this season and there are two non-league sides in round five for the first time ever.

United visit second-tier Blackburn Rovers on Sunday and having been stung by an FA Cup defeat at Newcastle United during his first season at Chelsea, Mourinho is determined not to take unnecessary risks.

"Maybe we don't have as many English managers with that culture as we should," he told reporters following United's 3-0 Europa League win over Saint-Etienne on Thursday.

"Maybe we foreign managers, not everybody studies and understands the culture of this country. In my case, I had immediately that situation with the match at Newcastle, so for me it was a lesson."