The Cameroon striker was below his usual deadly best in Saturday's 1-0 loss to Everton at Goodison Park, missing a couple of solid chances, but Mikel feels he is too good a player not to show his absolute top quality once he settles fully in London.
"Samuel is a great player, a fantastic player," Mikel said.
"You could see the way he played, he created some fantastic chances. That is why the manager brought him in. Obviously he has a lot of trust and belief in him."
He added: "The English league is very difficult to adapt to and this was the first game for him and he has done pretty well.
"Chelsea was my first real professional club and it took me six months to a year to adapt, but I think someone like Eto'o, who is well experienced and has played in so many leagues, won't take very long.
"I think he looked a bit sharp so it won't take him long to get back into his fitness. He is a world-class player, a fantastic guy. We just have to keep playing with him and helping him to adapt to the Premier League.
"He tries to give his experience so we have to keep working with him, keep playing with him and trying to help him to fit in."