London - Combining predatory instincts with a street fighter's approach to duelling with defenders, Diego Costa has emerged as the unapologetically snarling face of Jose Mourinho's hugely successful Chelsea overhaul.
Prised away from Atletico Madrid for $49 million by Mourinho, who surely recognised a kindred spirit in the fiercely competitive and occasionally spiteful Brazil-born Spain international, Costa has been everything the Chelsea manager could have dreamt of in an explosive debut season in English football.
If the bruising Didier Drogba was the blunt instrument Mourinho favoured to bludgeon opponents into submission in his first spell as Chelsea boss, in Costa, likely to be the key figure in Sunday's League Cup final against Tottenham at Wembley, he has found an even more effective weapon.
After spending most of his first season bemoaning his lack of dynamic attacking options, Mourinho's eye was taken with the way Costa fought fire with fire during Chelsea's Champions League semi-final defeat against Atletico Madrid last season.
After receiving a typically full-blooded challenge from John Terry delivered with the intent of intimidating, Costa gamely took every bump and bruise inflicted by his markers, returning the compliment with some ferocious challenges of his own.
That tetchy encounter left a positive impression on Terry, who said: "I think everyone remembers the square-up we had in the first 10 minutes against Atletico Madrid and after it I thought 'fair play'."
Costa's ruthless drive comes from a desire to make up for lost time after a slow start to his career.
With 27 goals, Costa was the key figure in Atletico's La Liga title triumph last year, and he also helped Diego Simeone's side finish as Champions League runners-up.
Yet before then his highest goal tally in a season was 10 during a loan spell at Rayo Vallecano and his breakthrough at Atletico only came in 2013 when he emerged from team-mate Radamel Falcao's shadow to score in a Copa del Rey final win over Real Madrid.
Given the 26-year-old's no-holds-barred style, it is little surprise he has fared so well in the rough and tumble Premier League.
Costa has fired the Blues to the top of the Premier League with 17 goals in just 20 appearances, while also earning widespread criticism after being handed a three-match ban for his cynical stamp on Liverpool's Emre Can in the League Cup semi-finals.
Like Mourinho, he has demonstrated a refusal to play by the sport's accepted conventions, no matter what the perception of his aggressive approach.
He responded to his suspension for the Can incident by clattering into Terry in the next training session, which can hardly have surprised the veteran defender given his colleague's call to arms during his first day at the club's Cobham headquarters.
"I'm very happy to be playing for Chelsea, but there will be times when I frustrate and annoy you, the Daily Telegraph quoted Costa as telling his team-mates.
"I will fight for every ball, every goal and I will get banned during the season.
"But I will also win you more points than you had last year and we will win trophies."
So far Costa has been true to that battle cry and this weekend he has the opportunity to deliver the silverware as well.