Former Manchester United defender Paul Parker has said Marcus Rashford must improve if he wants to be the Red Devils' primary striker.
The Norwegian is trusting Rashford and Anthony Martial to score goals, but the two-time Premier League winner has said the 21-year-old is "not doing enough" in his position.
Speaking to Alexander Netherton of Goal, Parker said Rashford needs to continue his development and that United should consider signing a new No. 9 similar to former striker Andy Cole.
"The hardest thing about United is trying to work out the direction they want to play.
"They need to find a centre forward who has a lot of pace, maybe like Andy Cole. When Cole came from Newcastle United he did so as a natural goalscorer, but he was able to adapt, to drop deep and link up with play in midfield.
"Does Rashford score tap-ins?
"He's still learning. You don't have to go off stats, you look at how the game is. He's not doing enough."
Mason Greenwood opened his goalscoring account for the season on Thursday during the 1-0 win over Astana in the UEFA Europa League. The 17-year-old played on the right of the attack, allowing Rashford to feature as the striker. The Mancunian missed several chances in the box, but Greenwood finished like a veteran when his opportunity presented itself.
Parker added Solskjaer was correct to sell Lukaku, but he said Rashford needs someone to teach him the dynamics of being a striker at Old Trafford.
"Should United have kept Lukaku? No. He could never change enough to become a United player," Parker said. "Rashford needs a mentor. Someone like Solskjaer or Mark Hughes, who could drop deep into midfield. Even someone like Eric Cantona or Teddy Sheringham would suit the squad."
Rashford's range of abilities and his lightning pace can terrify defenders, but his weakness has always been his finishing. The player came through the United ranks as a winger, and it wasn't until he broke into the first-team squad that he began to play in the centre.
The forward is young, despite playing over 100 games for United, and there's time for him to develop into a predatory striker. He has three goals in five league matches.
Solskjaer is likely to rotate his striking options this season, and with Greenwood already considered a good finisher, the rookie could be given his chance to lead the line at Old Trafford.