The Cameroon international had a debut to forget in the 1-0 defeat at Everton - Jose Mourinho's first loss in his second spell at the club - and looked a poor imitation of the player who had successful spells at Barcelona and Inter Milan.
Two extortionately paid seasons with Russian side Anzhi Makhachkala may have dulled the senses of the 32-year-old but Mikel predicts it will not be long before Eto'o is striking fear into defences again.
"Samuel is a great player, a fantastic player. You could see the way he played, he created some fantastic chances," the Nigeria international told Press Association Sport.
"That is why the manager brought him in. Obviously he has a lot of trust and belief in him.
"Let's wait and see, 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."
Source: PA
Source: PA