Anthony Martial scores the second goal for Manchester United during the Barclays Premier League match against Southampton ath the St Mary's Stadium, Sept 20, 2015. [Photo/Agencies]

LONDON - Paying a record fee that could eventually rise to 58.8 million pounds ($91.35 million) for a 19-year-old Frenchman many British pundits had barely heard of may have left Manchester United open to ridicule. But few are laughing now.

Especially their Premier League title rivals, after Anthony Martial, the world's most expensive teenage footballer, added two more goals at Southampton on Sunday to the one on his debut against Liverpool.

Each has been taken with the sure touch and composure of a veteran.

Before he moved from cash-strapped AS Monaco on the final day of the transfer window, United had failed to score more than one goal in any of their opening four league games and were looking in vain to Wayne Rooney for inspiration.

Six in the subsequent two matches have helped gloss over the fact that the United and England captain is without a Premier League goal since the start of April.

And with Dutchman Memphis Depay, 21, proving another exciting attacking acquisition after joining from PSV Eindhoven, the club appear to have recovered some of the youthful flair always previously associated with Old Trafford.

Gary Neville, once part of the famed "Class of '92" with David Beckham, Ryan Giggs, Paul Scholes and others, watched the 3-2 win at Southampton in his role as a Sky Sports pundit and was among those admitting to shock that Martial has done so much so soon.

"He's made a great impression," Neville said.

"United have always had pace up front and at least with him there is that threat again.

"Could he step up to being a one-in-two (games) man? I never thought he'd even be close to that but he's shown in the first couple of weeks he's got the composure to score goals."

United midfielder Morgan Schneiderlin confirmed the impression that his fellow countryman is mature beyond his years.

"He's like you see him in a game, very calm, very relaxed...an amazing talent," he said.

"Many people will have been a bit (surprised) because of the prize tag but he's a very intelligent guy and he will be a great player for the future of Manchester United."

It was left to the wise old manager, Louis van Gaal, to try to damped down some of the excitement, but even the Dutchman could not conceal his pleasure and pride at a player he went out on an expensive limb for.

"Anthony Martial is already special because we paid a lot of money for him," he told reporters.

"He's very important for us already.

"In three matches he has shown a lot. I am very happy with him but we and he have to keep our feet on the ground." ($1 = 0.6437 pounds)