Ross Barkley could become the best player in English football if the Everton man can add more goals to his game, says teammate Romelu Lukaku.

Barkley, 23, scored a goal and was named man of the match in the Toffees' 2-0 defeat of West Ham on Sunday, and has long been considered one of England's most promising talents.

Consistency has been an issue, however, with the Everton youth product having been dropped from manager Ronald Koeman's starting XI at Manchester City just two rounds before the Hammers triumph. And Lukaku highlighted the heights Barkley could reach with a few improvements to his game.

"I think the manager has been hard on him because he knows that Ross has the quality, he just needs to be more productive," Lukaku told multiple outlets.

"He has got loads of qualities, especially in the No. 10 positions. You expect goals and assists from them. He was productive today and that is what we need from him. When you see the firepower we have up front, we need more from Ross. We need more from myself as well and we are demanding from each other. That is the only way you can reach the top."

Lukaku says he often speaks to Barkley during training, and has given him tips on how he can evolve.

"When we do the finishing or have the small games, I will just tell him to keep his eyes open and play with his head up. He can see much more then, he can see where the space is and he can play the pass or shoot himself. The decision making has to be better. When he gets that, you are talking about a fantastic player."

Ross Barkley scored a goal in Everton's 2-0 defeat of West Ham on Sunday. Tony McArdle/Everton FC via Getty Images

Lukaku then added the sky is the limit for Barkley if he can put it all together in the future.

"At the minute, the players who play in his position -- like Dele Alli and Wayne Rooney -- they have got goals in them. I think Ross has to get more goals and more assists than he has been doing. If he does that, then he is going to play.

"Ross, to me, if he fulfills his potential, you are talking about the best player in English football. He has got everything. He has got power, he has got technique, he can shoot with both feet. He is fast, he can pick a pass. The manager has been working with him so he makes the right decisions on the pitch. Who is going to stop him?"