Chelsea's 3-1 victory over Manchester United on Sunday was Mourinho's 100th in the Premier League, making him the quickest manager to reach the milestone, achieving it in just 142 games. Sir Alex Ferguson had held the previous record, hitting his century after 162 matches.
That Mourinho's own achievement has taken some of the spotlight from him will not worry Eto'o one bit, though. The Cameroon international has now proved the difference for his club in vital wins over Liverpool and United within the past month, a sign that he is finally beginning to settle in West London.
Chelsea's victory over their old foe United points to one thing—this team means business.
Indeed, the contrast in fortunes between Mourinho's Blues and United on Sunday was significant. David Moyes' side are supposed to be the reigning champions, yet they had very little to offer at Stamford Bridge and were second best, as the scoreline suggests.
While Chelsea played with energy and zip, the champions appeared lethargic and off the pace. Were Chelsea a little more clinical, it could have been a rout. In fact, it should have been.
This was Eto'o's finest performance in a blue shirt since his arrival from Anzhi Makhachkala—a display brimming with confidence and an end product. All three of his goals were dispatched expertly, and for once, it was those behind him who were lacking a little composure in front of goal.
Oscar, Eden Hazard, Willian and Ramires all proved wasteful at times, but a rare off day when it came to their goals tally cannot take the gloss off what was a dominant performance.
Rather than appear straddled by the extra pressure, Chelsea thrived on it, sending out a clear message to those around them that they will have a major say in where the Premier League trophy resides come May.
While United appear to be a team in decline, the Blues are very much on an upward trajectory.
Without their own leader supreme, the Red Devils are struggling as they adjust to a new era after 26 years of Sir Alex at the helm. Mourinho is back in West London and Chelsea's transition now looks close to being over.
There are some areas that need to be addressed, although the Blues now have the look of a team ready to win trophies consistently.
Years of managerial changes and player turnover have scuppered their plans for domination since Mourinho's first spell, and now, they are busy making up for lost time.
John Terry noted in his post-match interview with Sky Sports that in years gone by, when the Blues have been struggling, it's games against United that have shown where they stood in the Premier League's hierarchy.
Using this latest encounter as the barometer, they are now close to where they want to be, breaking records in the process.
If Eto'o's goalscoring form continues, it shouldn't take too long before Mourinho hits a double century in the Premier League.
Garry Hayes is Bleacher Report's lead Chelsea correspondent and will be following the club from a London base throughout the 2013-14 season. Follow him on Twitter here @garryhayes