In two years there has only been one blemish on Jose Mourinho's record - a 2-1 defeat to Benfica in the 2004 Portuguese Cup Final. That aside, his Porto team won everything they entered: two Portuguese league titles, the 2003 Portuguese Cup, the Uefa Cup and the Champions League.
When he arrived at Chelsea in the summer, proclaiming himself a "special one", there were sneers. English football, it was felt, would find him out. It hasn't.
Mourinho has joined a club that has won one league title in its history, and nothing in four years, and taken them to the point that people are mentioning the quadruple - the three domestic trophies and the Champions League. On Saturday Chelsea will expect to maintain their grip on the Premiership when they face Newcastle United, to whom they have not lost at Stamford Bridge for 18 years. The visitors will also have to face the league leaders without the injured Alan Shearer and Nicky Butt.
Admittedly, most discussion of them possibly winning all four is in the sense of "they'll never do it", but when pressed on the point after seeing Chelsea beat his Fulham side on Tuesday night, Chris Coleman could find no reason why not beyond an apparent gut-feeling that it just wasn't seemly.
"They've enough quality in their squad," he said, "but it'll be hard for them to win all four. I think they'll win the Premiership, and possibly the Champions League, and they're in the semi-final of the Carling Cup, so they could win that as well."
It is a measure of how difficult the achievement is, though, of how much luck as well as ability is required, that only four European sides have ever done the double of Champions League and domestic league in the same season, and of those only Manchester United have also added their domestic cup.
For Chelsea, there must, Sir Alex Ferguson said this week, come a blip, but then he said that about Arsenal last season, and it is only in the past month that the Gunners have wobbled. It is a truth with which English football is struggling to come to terms, but the fact is that the distribution of resources is now so weighted towards the top three that blips are no longer inevitable. Football's first century brought only four league and cup doubles, but there have been five in the last decade, and that is no coincidence.
The likes of Chelsea, Manchester United and Arsenal can rest players against the lesser clubs, and by and large their line-up will still be stronger than their opponents'. The constant battering grind of the Football League now exists largely in the memory, and the squads of the top clubs are such that injuries are not the disasters they once were. With their unprecedented wealth, Chelsea have amassed such a pool of talent that it is hard to know where their first team ends and their reserves begin.
Mourinho said on Friday he would bring back Petr Cech, Paulo Ferreira, Frank Lampard and possibly Eidur Gudjohnsen and William Gallas for Saturday's game, but there was no sense on Tuesday night that Chelsea were without five regular first-teamers.
In that, Chelsea are unique in England: there remains a clear drop-off from United's first-team to the likes of David Bellion and Keiran Richardson, while few of Arsenal's reserves are out of their teens. The depth of Chelsea's squad is unique, too, in history, and that is why the quadruple, ludicrous as it sounds and impossible as it would have been even 10 years ago, is just about within their capabilities. Even Mourinho, though, knows that unblemished seasons are so rare as to be all but non-existent.