The 25-year-old had the first and the final say in a nine-goal thriller at Goodison Park as he continues his effortless adaptation to life in the Premier League.
Most were instead primed to observe just how Jose Mourinho’s men would cope without a fully fit version of their new striker against a team boasting two more he controversially cast out over the summer. Everton had triumphed in this fixture without Romelu Lukaku and Samuel Eto’o last season and both men seemed determined not to let this opportunity pass.
Costa did start. Eto'o later had his moment from the bench, but not before the Brazil-born Spaniard took just 35 seconds to relegate all other subplots to the realm of insignificance. With his third shot since arriving in the Premier League he scored his third goal, setting Chelsea on the way to a title statement at least the equal of Manchester City’s 3-1 defeat of Liverpool five days earlier.
Sadly the 100 percent conversion rate does not endure, but Costa still emerged from Goodison Park with his lethal aura enhanced. In a match of nine goals he was the single biggest threat and had the first and final say.
Mourinho, so often loathe to single out individuals for public praise when his teams win, made no effort to hide his delight with Costa.
"It was a fantastic performance in every aspect," the Chelsea boss said. "I remember him tackling [Seamus] Coleman in the first half on the edge of our box. He recovered balls, he held the ball, he was aggressive, he was face-to-face with [Tim] Howard three times and scored two goals. His movement, his quality, everything was really good."
In fact, Costa was face-to-face with Howard twice more over the course of the afternoon: in the 67th minute, when the livid American charged from his line and grabbed the 25-year-old by the collar for goading Coleman in the wake of the Irishman’s unfortunate own goal, and moments after the final whistle, when the Everton goalkeeper embraced his opponent as a beaten man.
Howard’s rage was uncharacteristic and hinted that Costa had achieved more than simply scoring against him. The Chelsea striker single-handedly tormented the Everton defense with his movement, physicality, direct running and tireless workrate. Few have ever made Phil Jagielka and Sylvain Distin look so hapless on home turf.
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Everton employed a number of methods to try to slow Costa down. According to Mourinho, this included "chasing cards" from referee Jonathan Moss. Coleman briefly got under the skin during a 56th minute altercation which saw the 44 million man euro booked and prompted the gloating celebration of the Irishman’s own goal, prompting Roberto Martinez to afterward accuse the Chelsea striker of a lack of respect.
In truth it would be a surprise if the mala leche — literally "bad milk" or "nastiness," in Spanish — that became associated with Costa’s game in La Liga does not bubble to the surface from time to time at Chelsea, but his aggression at Goodison Park was controlled, the servant rather than the master of his talent. It was a reality hammered home by his astonishingly composed second goal in the final minute of the match.
Even those who looked at Costa’s skill set and proclaimed him born for English football may not have expected him to prove it so quickly. The great Didier Drogba found the net just once in his first six Premier League games and only became a prolific goal-scorer in his third season.
That said, Mourinho saw the key difference between the two men from the start. "When Didier joined us, he was playing in the French league, having played just a couple of matches with Marseille in the Champions League," the Chelsea boss told reporters in July. "He was not even playing in World Cups with the Ivory Coast. Diego is made. Physically, mentally, Diego is an end product."
Drogba, of course, is back on the books at Stamford Bridge, but on this evidence his primary role will be Costa’s mentor rather than his rival. Loic Remy may also arrive to replace Fernando Torres before Monday’s transfer deadline, but Chelsea officials will have to dig beyond the evidence of the season's first three games to convince him he is truly required.
As on so many occasions for Atletico Madrid, Costa on Saturday proved a match-winner even when apparently hampered by injury. Such commitment to the cause eventually caught up with him at the worst possible time last season and ruined his World Cup with Spain, but Mourinho has the resources to be able manage his star man more carefully than Diego Simeone.
Even more importantly, the Special One finally has a striker he admires and believes in. As Chelsea surveys its rivals from the top of the Premier League and Costa surveys his rivals from the top of the goal charts, that is the only thing that matters.
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