Jose Mourinho warns Manchester United's form may not survive through busy fixture schedule

United are the only Premier League team still with a 100 per cent record

Jose Mourinho's side sit top of the Premier League table heading into the international break (Getty)

Jose Mourinho has warned that Manchester United may not be able to maintain their excellent form once they are forced to play twice a week.

United extended their perfect start to the new Premier League season on Saturday with a hard-fought 2-0 victory over Leicester City.

Three victories in three league games and a healthy goal difference have ensured that Mourinho’s side enter the September international break as the top flight’s early pace-setters.

The United manager, however, believes it will be difficult for his players to sustain the same level of intensity once their cup commitments kick in next month.

“If I have one week to prepare a match, my team is always very good,” Mourinho said after his side’s win on Saturday. “You have time to organise a week of work, going through every item of the game.

“When you start playing every two days, every three days, it's more based on what you build during pre-season and what you build during these weeks.”

United’s return to the Champions League, secured with last season’s Europa League triumph, begins with a midweek visit from Basel on 12 September.

The following week, their defence of the EFL Cup begins with a third-round tie against Championship side Burton Albion.

“From now, no more ‘clean weeks’,” Mourinho said. “From now, every week has a mid-week match until we are out of one of the cups.

“I think my team is the mirror of the work we are doing in clean weeks, when we can train five days and go through every item of the game plan.”