United signed Lukaku from Everton in 2017 in a deal worth £75m but after an impressive first season the Belgian striker has lost his place in the starting line-up this campaign.
Matic continues to impress but Sharpe says the Serbian has ‘lost a yard’ and could be replaced by French World Cup winner Kante report the Metro.
‘They have to go out and buy ready-made world-class players,’ Sharpe told talkSPORT. ‘They’ve got a few young players who are coming through, (Scott) McTominay looks really good.
‘There are a few young players in the team so they need ready-made, experienced, world-class players to put them back on that sort of level and stage. ‘I’m not sure it’s really worked out for Lukaku, a world-class centre-forward would be great.
‘Defensively they look a little bit uncertain so maybe a centre-half. If I was at United, I’d probably look at swapping Matic, he’s been brilliant but he’s probably lost a yard. ‘I’d go out and spend some money and get Kante because they don’t seem to fancy him at Chelsea.’
An under-par Manchester United clinched a 2-1 victory over West Ham on Saturday thanks to two Paul Pogba penalties.
Despite the win, Solskjaer – who was appointed United’s permanent manager last month – said: “They played better than us, it is fair to say, I don’t think anyone will disagree.
“Sometimes you get more than you deserve and today is one of those nights.”