London - Manchester United on Tuesday confirmed the signing of 19-year-old French striker Anthony Martial from Monaco on a four-year contract with an option for a further year.
"Manchester United is delighted to announce that Anthony Martial has completed his transfer from AS Monaco," the club announced on their website.
United did not disclose the transfer fee, but British media reports said it was €49 million - a record for a teenage player - with reports in France suggesting it could rise to €80 million.
"I am so excited to be joining Manchester United," said Martial. "I have enjoyed my time at AS Monaco and I would like to thank them and the fans for everything they have done for me."
News of United's move for Martial sent shockwaves across European football, with the former Lyon youngster having played just 52 Ligue 1 games and scored 11 goals in his fledgling career.
But despite United having struggled for goals in the season to date, manager Louis van Gaal suggested that he would be given a gentle introduction to English football.
"Anthony is a naturally talented, young, multi-functional forward with great potential," Van Gaal told the club website. "We have been watching him for a while now and he has developed immensely during his time at AS Monaco.
"I am delighted he has joined Manchester United as I believe this is the right club for him to continue his development as a young player.
"He has all the attributes to become a top football player; however we need to give him time to adjust to his new environment and the rhythm of the Premier League."
Martial joined Monaco from Lyon for around €5 million in 2013 and broke into the first team only last season, scoring 12 goals in 46 appearances.
He was handed his first France call-up for the forthcoming friendlies with Portugal and Serbia and was allowed to leave their Clairefontaine training base on Monday in order to sign his contract and undergo a medical.
"I have always wanted to play in the Premier League and to join the biggest club in the world is what every young footballer dreams of," added Martial, who has represented France at every youth level from under-16 to under-21.
"I am looking forward to meeting my new team-mates and working with Louis van Gaal, who has achieved so much in his career."