The Red Devils are currently preparing for their third campaign under the Portuguese coach following his appointment at Old Trafford back in May 2016.
Manchester United endured something of a disappointing campaign last term as they ended up in second place in the Premier League table and without a trophy under the Portuguese coach.
The Red Devils have been busy in the summer transfer window, with Manchester United having brought in Fred, Diogo Dalot and Lee Grant as they prepare for the new season.
Mourinho is aiming to steer Manchester United to a genuine Premier League title challenge next season as the Red Devils look to win the trophy for the first time since 2013.
However, Jenas feels that the situation at Old Trafford is far from ideal ahead of the start of the new campaign.
Speaking in an interview with BBC Sport, Jenas said: “I don’t see it ending well.
“There are too many internal issues with existing players, issues over their style of play, and also issues with potential signings supposedly saying they do not want to go and play there for him because of that style of play.
“United fans are not convinced by the football they play under him, or where they are heading under his leadership, so it is going to be an interesting few months.”
Manchester United will kick off the new Premier League season when they host Leicester City at Old Trafford on Friday night.
The Red Devils have not won the Premier League since their final triumph under Sir Alex Ferguson back in 2013.
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news