Kai Havertz might be just 21 but Chelsea have acquired a special talent by bringing in the German from Bayer Leverkusen.

He looks set to make his Premier League debut at Brighton and Hove Albion on Monday evening, with head coach Frank Lampard expecting big things.

But what made Havertz such a golden boy of the Bundesliga, and why did Chelsea feel compelled to lavish a reported club-record fee to bring him to Stamford Bridge?

Can the player described by Lampard as being remarkably "humble and down to earth" impose a big footballing personality on the English game?

Using Opta data, we look in detail at his career so far, and the qualities he will add to the ambitious Blues.

So much, so young

Havertz made his Bundesliga debut at the age of 17 years, four months and four days, which at the time made him Leverkusen's youngest-ever player in the competition - a record broken by Florian Wirtz in May 2020.

He soon became their youngest Bundesliga scorer too, but Wirtz also swiped that record away in June.

What soon became clear at Leverkusen was that Havertz was mature enough to handle regular first-team football, and at 20 years, six months and three days, he became the youngest player in history to tot up 100 Bundesliga appearances.

Whose ton-up record did he beat? Only that of fellow Chelsea newcomer Timo Werner, by 16 days.

Could he be a slow starter?

Opta statistics show that 27 of Havertz's 36 goals in his Bundesliga career came in the second part of the season, with 11 of those goals (31 per cent) coming in the month of May.

Left-leaning away-day specialist

Havertz, often compared to former Chelsea and Leverkusen star Michael Ballack, produced some of his best form away from the BayArena during his Bundesliga days.

Certainly, in terms of goals, he was at his most productive on the road for Die Werkself.

Of the 46 goals he netted across all competitions for Leverkusen, 28 came in away games, with 16 scored at home and two netted at neutral grounds.

Predominantly a left-footed player, the emerging maestro netted 33 goals with his favoured foot, seven with his right, and added six headers, with showreels of his goals for Leverkusen demonstrating Havertz is both clinical and creative with his finishing.

But can he really fill the gap left by Willian?

Chelsea wanted to keep their Brazil winger but lost him to Arsenal. Not to worry; in Havertz they have landed a ready-made replacement who is 11 years younger than Willian and improving season by season.

Both have their own individual qualities and separate subtleties to their performances, but in the starkest terms Chelsea look to have landed an upgrade.

Havertz's 36 goals and 22 assists in 118 Bundesliga games for Leverkusen compares favourably with Willian's 37 goals and 33 assists in 234 Premier League outings with Chelsea.

The incoming Germany international edged it last season in terms of passing accuracy in the opposition half - 82.83 per cent to Willian's 80.91 per cent - and more touches in the oppositon penalty area - Havertz having 140 in 30 games and Willian 128 in 36 matches.

Willian can be shown to be a more successful dribbler, a player who won more duels and a more productive crosser of the ball.

But Chelsea have no doubts about the class of the young man who could drive their midfield forward for years to come.

As Lampard said last week: "He's a different player to what I was but, when it's an attacking midfielder that scores goals, obviously I certainly sit up and take notice."