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."
Eto'o's debut could have got off to the perfect start after only five minutes, but he directed a close-range header from Ramires' cross wastefully wide.
More embarrassingly for the Cameroonian, and probably as a result of trying too hard, he ballooned one shot into the upper tier of the Gwladys Street end.
He would have scored into an open net had Everton's own debutant Gareth Barry not slid in to rescue goalkeeper Tim Howard's blushes when, in trying to pass sideways out of his six-yard area, he picked out Andre Schurrle.
But all-in-all it was not the debut people were expecting as Steven Naismith bundled home a header from close range on the stroke of half-time.
The closest Everton came to scoring after that was when Leighton Baines rattled the angle of crossbar and post with a 90th-minute free-kick.
Chelsea created plenty of chances and Mikel said that meant it was difficult to know what to fix.
"It is about how we bounce back. Sometimes when you know what you've done wrong it is easy to bounce back," he said.
"We need to go back to training and try to find out what we didn't do - although everyone knows what we didn't do, we didn't score goals."
Mourinho felt his side should have won but stressed he was confident the goals would start flowing once his side got up to speed with his methods.
"We train movement, we train dynamics, we train attacking organisation, we train finishing situations related to the position of the players and the profile of situations," said the Portuguese.
"The players are good so sooner or later we will score goals.
"If they don't have the killer instinct they have to get it but I think they have it.
"I think Samuel has had it all his career and the situations he had in the game made me very happy because it looked for me like he had a good understanding with the team.
"I think (Eden) Hazard is playing very well. The kid is having a very good evolution and is showing maturity and ambition and I am very happy. So, no problem.
"Normally the team has to be the face of their manager and it is easier to be that after four or five months than six weeks.
"We have the profile of players we have and since the beginning I know that teams are incomparable (with his previous Chelsea era).
"This is a different team of players and we have to play with our strength and that is exactly what we did in this game but we have to put the ball in the net.
"I encourage them because we have an identity and we played to our identity.
"We have to play to our qualities and we did but they have to be effective and score goals.
"One day we won't deserve to win and we will win, I am sure."
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- Jose Mourinho