The Brazilian born striker pledged allegiance to Spain before the World Cup but he struggled in his homeland to find his best form.
In fact Costa is yet to fire for Spain. In his six caps for Spain he is yet to score, which is in stark contrast to his form at club level.
He netted 36 times for Atletico Madrid last season and has started in similar style for new club Chelsea. Since his £32 million move from Spain Costa has found the back of the net nine times in as many games - leaving Chelsea fans purring and Premier League defences quaking.
But in their last game, a shock defeat against Slovakia in European Championship qualifying, he was again poor.
In fact, he was outshone, by substitute Paco Alcacer.
The Valencia man entered the fray in the 71st minute and looked to have salvaged a point for Spain with an 82nd minute equaliser.
However a goal from former Chelsea youngster Miroslav Stoch won the tie for Slovakia.
With his 20 minute cameo many a Spain fan decided they would in fact prefer to see Alcacer start in Spain's next game against Luxembourg.
However Costa has the backing of the player trying to replace him.
Alcacer has been waxing lyrical about the Chelsea striker this week, telling reporters in Spain:
'He will score soon. I have a very high opinion of him. These good and bad patches are quite normal and soon his first goal will come."
Costa may have to start firing soon, or risk watching on as Alcacer takes the reign as Spain's number one striker.