It's not just in the Premier League where the rumbles of Chelsea manager Andre Villas-Boas's influence are being felt.
In the eight months that have passed since 'AVB' led Porto to Europa League glory against Braga in Dublin, the axis of power in Portuguese football has tipped one way and then another.
Back in spring, Porto were untouchable. They had just become only the second team in Portugal's history to complete a league season unbeaten, after Englishman Jimmy Hagan's Benfica in 1972-73.
Then the coach who had said leading Porto "surpasses all my childhood dreams" stunned Portugal by leaving for the bright lights of the Premier League and Stamford Bridge.
His replacement was always likely to be on a hiding to nothing. It wasn't just Villas-Boas's results that spoke volumes for his work. The swagger of Porto's squad and their extraordinary dressing-room spirit struck fear into opponents. His departure left a gaping hole.
Porto president Jorge Nuno Pinto da Costa attempted to fill it via continuity. He immediately appointed Villas-Boas's assistant, Vitor Pereira, and retained most of the backroom staff. Pereira was also given £36m of new players to work with.
The pallid performances of Porto's eagerly awaited Champions League return were a warning flag. Star forward Hulk called the goalless draw with Zenit that eliminated Porto "our best collective display of the season". It underlined how internal expectations, and standards, had dropped.
The Portuguese media quickly sensed Pereira was not the totemic leader Villas-Boas had been. He is a decent coach and well liked, but his rhetoric rarely inspires in the way his predecessor's had.
It seems ludicrous that Pereira is under threat almost halfway through a league campaign in which Porto - like Benfica - remain unbeaten. Yet context is everything in a country where a club outside "os tres grandes" - "the big three" - have been crowned champions just twice.
At present, it's almost a mini version of the Real Madrid and Barcelona rivalry.
The standards of Benfica and Porto have been so high in recent seasons that even the smallest slip is a relative disaster. The knife-sharpeners point out that Pereira's side have already dropped more points as Villas-Boas's men did in the whole of last season - eight, as opposed to last season's total of six.
It will come as little surprise to Manchester United fans to hear Benfica have upped their game this season in response. Coach Jorge Jesus's secret has been to not overreact to last season's relative failure at the Luz.
Benfica resisted the temptation to make wholesale changes in the summer and have been rewarded. Their regular 4-4-2 formation gave way to the stylish five-man midfield displayed in the 2-2 draw with Manchester United at Old Trafford in the Champions League.
New signing Axel Witsel has added power and finesse and United's reported interest in playmaker Nicolas Gaitan isn't hard to fathom either.
The team has plenty of goals in it too. Former Bolton loanee Rodrigo has weighed in well on his return. Paraguay's Oscar Cardozo - a scorer against United - is no longer an automatic choice despite having managed 22 European goals for the club. It is a reflection of Benfica's options.
Porto also have to contend with a challenge from the other side of the capital.
Sporting Clube de Portugal were in sporting and institutional crisis last season, and finished 36 points behind the champions.
New president Luis Godinho Lopes authorised a summer rebuild, spending just under £30m, a huge figure by Sporting's standards. New coach Domingos Paciencia - like Villas-Boas, a product of Sir Bobby Robson's days at Porto - has overseen major changes.
Brazil midfielder Elias joined for a record fee from Atletico Madrid, while Dutch pair Ricky van Wolfswinkel and Stijn Schaars have been big hits as Sporting have entertained at the same time as climbing the table.
That Sporting's under-19 side have been so impressive in the NextGen Series shows the club's traditions of youth development have not been neglected. Portugal's most fertile academy has spawned the likes of Cristiano Ronaldo, Luis Figo and Nani.
After Sporting finished top of its group in NextGen, thrashing Liverpool both home (5-1) and away (3-0), Europe's scouts are licking their lips again. The current crop includes towering London-born defender Tiago Ilori, who made his first-team debut against Leiria in October.
All in all, Portuguese fans can anticipate a far closer second half of the season than last time out. Economics mean Portugal will never be the most open of championships, but its health is definitely improving.