Manchester United manager Louis van Gaal admitted he was considering substituting Juan Mata before the Spaniard scored the winning goal in their 1-0 triumph against Watford at Old Trafford. The 27-year-old midfielder was the captain of a youthful United side for the Premier League fixture, and scored the only goal of the game with a beautifully-directed freekick in the 83rd minute.

Van Gaal revealed he was contemplating whether to introduce Jesse Lingard into the fray late into the game at the expense of Mata or Ander Herrera, shortly before Mata gave United the lead.

"I was substituting Herrera and my second choice was Mata. But at that time we had the momentum, we were very attacking, so I didn't change at that moment. And that was good, because he could score the goal," the Dutchman told the BBC.

Van Gaal also said his decision to swap the positions of Marcus Rashford - who started the match as the lone central striker for United - and Anthony Martial - who was positioned out wide - proved to be pivotal in the outcome.

"I think that was the better change, because Anthony Martial was not in the match and Rashford was not in the match, so I changed them, then they were both in the match again," the United boss reflected after the game. "At that time, we got that momentum and at that time, I don't want to change any more."

United were somewhat fortunate to take all three points from the game, with Odion Ighalo guilty of spurning some great goal-scoring opportunities for the Hornets. But Van Gaal was thrilled with the efforts of his United side, which had an average age of just 23 years and 222 days.

The Dutchman, who started with 18-year-old Timothy Fosu-Mensah at centre-back, said: "It was very tough. Also the weather conditions didn't make for a good game. It was a heavy game, a physical game.

"I have to give a lot of compliments to my players. Because when it is a physical game and you can win that game on an important moment, because all of our competitors are losing, it is very important."

Victory at Old Trafford moves United level on points with their bitter rivals Manchester City, who were beaten by Liverpool at Anfield.