Manchester United manager Louis van Gaal has admitted he is experiencing the toughest moment of his career as he prepares to take on West Ham on Saturday with just one fit senior central defender. The team’s defense was already in a troubled state before Jonny Evans and Chris Smalling joined Phil Jones on the sidelines, and youngster Tyler Blackett was slapped with a suspension for his sending off in a disastrous 5-3 defeat at Leicester City last Sunday.

Now, just Marcos Rojo, who has started his United career at left-back, remains available for a United side that has won just once this season. Van Gaal concedes the situation is not what he envisaged when he took charge in the summer, but remains confident things will turn around.

“At this moment this is maybe my toughest job but we have to see in a year,” he said, according to Manchester United’s official website. “We cannot say it about one week with the injuries. As a manager you know already in advance that it's a big challenge. This club is in a transition. What you don't know in advance is what the hard moments will be.

“At the start we won all of our games but now we are in difficult circumstances. We should have won last weekend -- we had to win when we were 3-1 up. If we had we would have been two points off second place. But because of the loss you are now questioning me. If we won then it would have been different. We will overcome things -- the season lasts a long time.”

With options so thin on the ground, it had been speculated that Van Gaal could drop Daley Blind back into the backline or even rush midfielder Michael Carrick back to fitness as a makeshift central defender. Instead, Van Gaal insists that he will turn toward youth, and has called up Paddy McNair and Tom Thorpe from the Under-21 side.

“I don't like having too many left-sided defenders or left-footed players in defense,” he told MUTV about the possibility of fielding Blind alongside Rojo. “I think always of balance so [instead] I have to pick up a right-sided central defender from the youth education. Normally, I am always doing things like that. I have already said that we have a lot of vacancies when you buy only six players and let 14 players go.”

Following on the back of Leicester, West Ham are now the team looking to exploit Manchester United’s problems. And they could hardly be coming into the contest at Old Trafford in better form, following a superb 3-1 victory over Liverpool last weekend. New forward arrivals Enner Valencia and Diafra Sakho have both hit the ground running and breathed new life into a team that has previously earned Allardyce much criticism for its uninspiring style. Now Allardyce, despite suffering an injury blow with Cheikhou Kouyate being ruled out for six weeks, is targeting another major scalp.

"We need to make sure we limit their chances and use the possession we do have when we have it," he said, according to West Ham's official website. "We have to be as good at taking the ball off them as we were against Liverpool last week. We're going to have to dampen the outstanding talent that they do have and the exploit the defensive weaknesses."

Prediction: The contrast in the two parts of Manchester United’s team was quite spectacular last week. Led by Angel di Maria, United looked as exciting going forward as they have done in years, but defensively, with a heavily unbalanced team and individual errors aplenty, it was a calamity. Especially with West Ham missing the extra midfield solidity of the impressive Kouyate, United should again be able to score goals on Saturday.

But there is little chance of Van Gaal’s men keeping them out. Rojo is far from the most authoritative at center-back as it is, without being joined by a completely untested youngster. Blind could also struggle to control the tempo and protect the backline if he is confronted by the same performance Stewart Downing put in against Steven Gerrard a week ago. In front of Downing, the pace and vitality of Valencia and Sakho have transformed an attack that was all too predictable with Andy Carroll and Kevin Nolan. If West Ham can avoid being blown away early then they could well claim a point.

Manchester United 2-2 West Ham

Kickoff time: 10 a.m. EDT

TV channel: NBC Premier League Extra Time

Live stream: NBC Sports Live Extra