The Red Devils opted to sell the Belgian striker to Inter Milan in the summer transfer window after deeming him to be surplus to requirements at Old Trafford.
Manchester United opted not to bring in another striker in the summer transfer window to replace Lukaku, as they instead tied up deals for Daniel James, Aaron Wan-Bissaka and Harry Maguire.
That means that the Red Devils will be heavily reliant on the likes of Anthony Martial and Marcus Rashford up front until the January transfer window at the very least.
And former England star Shearer feels that Solskjaer has taken a big gamble by opting not to replace Lukaku in the summer window.
Writing in his column for The Sun, Shearer said: “For England, it is not a problem [that Rashford is not a natural number 9] because he will never play there ahead of Harry [Kane], and Marcus looked sharp against Bulgaria from the left.
“It is a bigger issue for United because they have taken a huge gamble by not replacing Lukaku.
“Going into the season with just Marcus, Martial and Mason Greenwood is very risky and that is a huge burden for those three to carry over a long campaign.”
Manchester United have made a mixed start to the new campaign, after having only won one of their opening four games.
The Red Devils have taken five points from a possible 12 and will return to Premier League action after the international break when they host Leicester City at Old Trafford on Saturday.
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