MANCHESTER, England -- Manchester United manager Ole Gunnar Solskjaer still intends to strengthen his attack despite Mason Greenwood's emergence this season.

Greenwood scored twice as United secured top spot in their Europa League group with a comfortable 4-0 win over AZ Alkmaar. The 18-year-old now has six goals in seven starts this term but Solskjaer is still on the look out for a striker.

"We're looking to strengthen in many positions," said Solskjaer. "If you look at our squad compared to others we're getting there but we need two or three players to have a squad with enough numbers to rotate throughout a long season and we'll see what we sign."

The bulk of Greenwood's minutes this season have come in the Europa League but after handing the teenager a first Premier League start of the season against Tottenham, Solskjaer insists he is ready for a prolonged run in the team.

"He played against Tottenham and he was class," said Solskjaer. "I'm not afraid of playing him in the Premier League, not at all. It is about sharing minutes and finding the right minutes. He is ready to play in Premier League."

Greenwood has work to do to displace either Anthony Martial or Marcus Rashford in Solskjaer's first XI but with a hectic Christmas schedule approaching, the United boss will be forced to rotate.

"I've probably said it all before, that's what he [Mason] does," said Solskjaer. "Tomorrow [Friday] he will probably go into training and score a few more. He has always done it.

"That is just natural for him. He is a natural footballer. The closer he gets to goal the more dangerous he is. Right-foot, left-foot, he is a nightmare for defenders.

"He needs to develop his heading. Then he can be a proper striker.

"I've seen a few good ones, I played with Wazza [Wayne Rooney], natural finishing he's one of the best I've seen."