Manchester United, for the second successive week, scraped three points at Old Trafford on Sunday afternoon. The Red Devils had goalkeeper David de Gea to thank for their narrow 2-1 victory over Everton, but the Spanish shot-stopper will be powerless to prevent Chelsea scoring a hatful of goals at the Theatre of Dreams later this month if Louis van Gaal sticks with both Robin van Persie and Radamel Falcao upfront.
The veteran Dutch coach must change his system in order to stand any realistic chance of nullifying the Premier League title favourites on October 26 - and with Falcao on the brink of exploding into life following his first Manchester United goal against the Toffees, Van Persie is the man who must make way for Michael Carrick or Marouane Fellaini.
Manchester United have defensive problems
Manchester United have started the season playing with one holding midfielder, Daley Blind, behind Ander Herrera and Angel Di Maria.
While going forwards they have looked very impressive at times, defensively Van Gaal's side are extremely vulnerable.
Because they're had a relatively kind start to the season, Van Gaal has been able to get away with playing Blind - a technically proficient holding midfielder, yes, but hardly a presence - as the team's only defensively-minded midfielder.
Van Gaal cannot play 4-1-2-1-2 against Chelsea
He might stick with the same system for United's next Premier League fixture against West Brom after the international break, but playing a 4-1-2-1-2 against Chelsea and Manchester City would prove catastrophic.
Blind, for all of his technical qualities, would be badly exposed against top-class Premier League midfielders like Nemanja Matic, Fernandinho or Yaya Toure - three stars who the Netherlands international will go head-to-head with over the forthcoming weeks.
He needs help - whether that's from Fellaini, Carrick or Darren Fletcher.
Chelsea and City are better teams
Van Gaal might not enjoy having to set his stall out to nullify Chelsea and City, but there's a considerable gulf in class between the Premier League's top two and the rest, as things stand, including United. And Van Gaal must acknowledge this fact.
The Red Devils are still adjusting to life under their new manager, but are beginning to show signs of slow and steady improvement. It's proving to be a lengthy process, however.
Phil Jones will make a difference
Admittedly their defensive concerns have not been helped by having so many of their top stars on the treatment table and United will look so much better when Phil Jones returns to the heart of defence.
The England international has been United's standout defender this season now that he's been encouraged to nail down his natural position as a centre-back - and the Red Devils will reap the rewards for years to come.
But a United back-four featuring Jones still requires protection - and Blind is not capable of providing it on his own, which is why Van Gaal has to withdraw one of his strikers.
Van Persie now in decline
Van Persie may have scored two goals in his last three matches, but he's been disappointing every time he's set foot on the pitch this term. It wasn't a dissimilar story last term under David Moyes, but Manchester United fans expected a little more from the £24 million striker at the start of this season.
Perhaps he's still working his way back to full fitness, but this is undoubtedly a formerly world-class striker now in the early stages of decline, and it wouldn't be a huge shock if he left Old Trafford within the next 18 months.
He no longer strikes fear into the hearts of opposition defenders. Rewind 24 months and he was, by some distance, the Premier League's best player and the main difference between Manchester United and rivals Manchester City as Sir Alex Ferguson went on to wrap up the club's 20th league title in record time.
Januzaj could return to fold
By dropping Van Persie and deploying another midfielder to partner Herrera and Blind, Van Gaal could also play with natural width for the first time this season: Di Maria on the left, and either Antonio Valencia or Adnan Januzaj on the right.
Most United fans will be hoping to see Januzaj given a chance to shine. The Belgian starlet is blessed with world-class talent but, sadly, has barely featured under his new manager this term.
Although the 19-year-old penned a new long-term deal with the Red Devils last season, he will grow increasingly frustrated if he continues finding himself on the substitutes' bench or, worse, in the Under-21 squad.
He's proved on several occasions this season that he's far too good to be playing Under-21 football; we're talking here about one of Manchester United's standout performers from last season.
Van Gaal must change system
Van Gaal's side currently lack balance and risk being humiliated against both Chelsea and Man City - two supremely balanced sides, with quality in all areas of the pitch - over the forthcoming weeks.
But the United boss can make his side much tougher to beat by changing his vulnerable system - starting by withdrawing the ineffective Van Persie.
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