While AC Milan has been in an ascent, the Roman empire has crumbled in west London, Russian oligarch Abramovich effectively becoming persona non grata in London after Vladimir Putin's decision to invade Ukraine.

Four days after Tomori went to Milan, Chelsea sacked manager Frank Lampard, and last month his Champions League-winning successor, Thomas Tuchel, has been run out of town.

Boehly-ball is flavour of the day at Stamford Bridge, with long-term thinker Graham Potter entrusted by the new owners with delivering short-term improvements for the Blues.

On and off the pitch, it's been a dizzying 21 months in west London since Tomori, in the midst of the pandemic, said farewell to Chelsea and 'Ciao!' to the Rossoneri.

There will be familiar faces for Tomori to greet when Milan arrive at San Siro for their Champions League showdown, but he is far from alone in having moved on. Kurt Zouma and Antonio Rudiger, erstwhile rivals to Tomori for a centre-back berth, have been among those to leave.

Born in Canada but raised in southern England, Tomori left Chelsea for Milan on January 22, 2021.

The deal, initially a loan, was struck in a week when the UK's home secretary Priti Patel announced an £800 fine for anyone attending a house party. A fortnight earlier, it was announced the Queen and Prince Philip had received their first COVID-19 jabs. They were very different times.

There's a new king in London town, these days, the first change of monarch for 70 years, but Chelsea kingpins come and go.

Tomori never reached that status, unlike Lampard, who as Derby County boss gave the young defender a leg up, taking him on loan from Chelsea before both were reunited in west London.

In this corresponding midweek four years ago, Tomori was lining up with Mason Mount for Lampard's Derby in a Championship game against Norwich City, the two Chelsea loanees helping the Rams to a 1-1 draw.

Now he is a major figure at the heart of Milan's title-winning backline, trusted by coach Stefano Pioli and admired by that great Rossonero, Paolo Maldini.

Tomori's world?

Milan has kept 14 clean sheets in domestic league action since the turn of the year, the joint-fewest of all teams in Europe's top five leagues (Serie A, Premier League, LaLiga, Ligue 1, Bundesliga).

Only Barcelona can match that total, while Chelsea has managed a relatively modest eight shut-outs.

Milan's goals-against tally of 18 in 27 Serie A games this year is five better, or meaner, than any side who have been in the Italian top flight throughout 2022, with Napoli next on that list.

Tomori has not played every game, it should be pointed out. In his 22 appearances, Milan has had nine clean sheets and shipped 13 goals.

Milan is stronger for his presence. Taking all competitions into account, and working on the basis of three points for a win in every game, Milan has averaged 2.0 points when Tomori has started, and 1.5 when he has not, since his debut.

Its average goals-against is 0.9 when he plays, and 1.3 when he does not, and the win percentage stands at 58.2 per cent with the 24 year-old in the XI, up from 46.7 per cent when he is either absent or a substitute.

Tomori only played 17 games for Chelsea, starting 15 of those, before the Premier League club decided his services were expendable.

World Cup in his sights

Perhaps he will have something to prove to Chelsea, but Tomori has arguably moved beyond that point. He is a Serie A champion, recently signed a contract that runs through to 2027 at San Siro, and could hardly be happier in Italy.

He has learned the language and is a starter with a long-standing giant of European football.

Tomori netted against Liverpool in the group stage last season, becoming only the third English player to score a Champions League goal against an English opponent while playing for a non-English side. How he'd love to put one past Chelsea on Wednesday, too.

If there is anyone Tomori might want to impress, it could be Gareth Southgate. He looks to rank among the possibles rather than the probables in terms of Southgate's England World Cup squad plans, having won just three senior caps so far.

Tomori has been "excited" by the trip to London, saying: "It's obviously an important game in this round of the Champions League, and going back to Chelsea and Stamford Bridge is going to be a great game for me."

He added: "It's just another chance for me, seeing some familiar faces, to show how I've developed. Seeing everyone will be nice. It will be a nice reunion of sorts, but I'm trying to think of it as just another game."

Tomori watches Chelsea games whenever he can, but not with any sense of envy, telling Milan's website: "The Premier League is, as people say, the best league in the world; but for me right now, being in Milan, playing in Serie A, learning the trade of nasty defending, per se, is where I'm comfortable at right now."

There it is, the Milan culture seeping into Tomori, the new guy in town learning from the cunning of that sly dog Zlatan Ibrahimovic, aching to pick up the tricks of the past masters.

So, Chelsea will recognise the returning familiar figure, but plenty has changed with Fikayo Tomori since he packed his bags and took his punt on this Italian odyssey.

Milan took his eye; he's been a hell of a buy. That's Tomori.