Costa, 25, became a household name last season with Atletico Madrid, where he hit 35 goals to spearhead Diego Simeone's side as they won the La Liga title and reached the Champions League final in an unprecedented season for Madrid's 'second' club.
Having changed his nationality from Brazilian to Spanish, Costa was expected to add a new dimension to Spain's already all-conquering side which had won three major tournaments in a row as they chased a fourth at the World Cup in brazil this summer. However, with no goals and two lethargic displays, Costa was one of the disappointments of the tournament - which made people doubt Chelsea's £32m move to land the striker.
Those doubters have been proven very, very wrong so far as Costa has hit the goal trail already in the Premier League, notching four goals in just three games to finally give Jose Mourinho the striker he craved so much last season. His powerful displays have given Chelsea the edge in the Premier League season so far, with many now believing that the Blues are the clear favourites to win the title off the back of Costa's goals.
Now on international duty with Spain, Costa is looking to continue that form as Vicente del Bosque's side take on France and Macedonia in the next week in friendlies and Euro 2016 qualifiers.
And, judging by this stunning finish in training, Costa will be in the goals once again for Spain. After holding off former Atletico team mate Juanfran, Costa draws Iker Casillas out of his goal before delicately dinking the ball over him and into the net.
This is the kind of finishing that made Mourinho pay £32m to land Costa, and we've already seen him exhibit his predatory instincts in England. Can anyone stop him?