Everton legend Graeme Sharp has backed young forward Dominic Calvert-Lewin to grab the opportunity to establish himself under Ronald Koeman, who has little choice but to put faith in the former Sheffield United star after failing to sign a replacement for Romelu Lukaku during the transfer window.

The Toffees were looking to bring in a powerful target man in order to replace Lukaku, who has enjoyed a bright start to life at Manchester United, but failed to bring in the likes of £25m-rated Olivier Giroud and Benfica forward Raul Jimenez, while an audacious move for Chelsea's forgotten man Diego Costa failed to come to pass.

Everton's failure to bring in a seasoned striker disappointed some supporters, but Sharp, who led the line for Everton during the most successful period of their history back in the mid-1980s, believes the lack of senior striking options will be prove to be beneficial to Calvert-Lewin, who now has the chance to "stake his claim" in the Everton first-team.

"The manager said he wanted another striker in the transfer window but Dominic has a great opportunity now to stake his claim," Sharp told the Liverpool Echo. "He has come back full of confidence after winning the World Cup for England Under-20s over the summer and he's hit the ground running.

"People have to remember he is only a young lad and there will be times when his form naturally dips, so we have to be patient with him.

"But, from what we've seen so far, he's impressed and long may that continue."

Koeman is clearly a fan of Calvert-Lewin and has seen fit to use the England Under-21 international in all of Everton's competitive fixtures so far. His encouraging performances may in turn bring greater pressure to produce as the season progresses, but Sharp believes the 20-year-old has the attributes necessary to make full use of the opportunity presented to him on Merseyside.

"There might be a bit more pressure on him now, but you've got to be careful with him," Sharp said. "The manager knows that as well – and he'll know the right times to play him.

"He's a confident boy. It's the hardest league in Europe to play in, so it's asking an awful lot to come in after coming from Sheffield United only this time last year.

"He's probably got his opportunity quicker than even he'd have thought. You have to take your hat off to him.

"He's got a fantastic leap, he's good in the air. He's also very quick and he can run the channels well. Obviously, there are parts of his game that he's still developing but that will come in time."

Dominic Calvert-Lewin and Antonio Rudiger
Calvert-Lewin has featured in all of Everton's competitive fixtures this season. Getty Images