Diego Costa will be disappointed to have learned of his omission from the Spain squad as Vicente Del Bosque plumped for other options.

His loss will ultimately prove Chelsea’s gain though as he looks to put a nightmare campaign behind him under new manager Antonio Conte next season.

Costa missed Chelsea’s final two Premier League fixtures with a hamstring injury and Del Bosque left out the fiery forward from his provisional 25-man list ahead of Euro 2016.

The Spain coach can revise that list before it must be set in stone at the end of the month, leaving Costa time to convince his boss of his fitness.

Fitness has proven a struggle for the Chelsea hitman this season and the roots of his problems in 2015-16 can be traced back to last summer.

Costa, much like at the end of this season, picked up an injury towards the end of term and then went off on holiday.

Bad moment: Diego Costa reacts to a missed chance
Training: Chelsea's Brazilian-born Spanish striker Diego Costa

However, the 27-year-old didn’t stick to his training regime and returned to England overweight and lacking sharpness.

To make matters worse, he was then spotted partying in Ibiza after the players were given a two-day break following Chelsea’s opening-day draw with Swansea.

Costa would later admit that those summer months were responsible for his shocking downturn in form as the Blues surrendered their Premier League title with a whimper.

Just months earlier, Costa had been scoring his 20th goal of a stunning debut campaign and terrorising defences up and down the land with his combative streetfighter style.

Following the departure of Jose Mourinho in December, an exit Costa and several others were criticised for facilitating, the Brazilian-born Spaniard finally got his groove back.

He ended the season with 12 goals. That’s not a very impressive number for a player of Costa’s quality, but even double figures looked a long shot during those dark days.

Chelsea's Premier League demise in perspective:

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Would Costa be in the Spain squad had he not been injured? It’s possible. But even when he has been fit and firing for his club, Costa has failed to impress at international level.

His Spain CV reads 10 caps and one goal, which came in a demolition job on Luxembourg, with his most recent outing coming against England in November.

Trouble seems to follow the firebrand forward around and the Spanish coaching staff have their reservations about his behaviour on the field.

His retrospective ban for clashing with Arsenal’s Laurent Koscielny and Gabriel didn’t go unnoticed by Del Bosque and he publicly blasted Costa’s antics at Stamford Bridge.

Remarkably, Costa has never been sent off in a Premier League game.

Duo: Head coach Vicente Del Bosque and Diego Costa
On the run: Kyle Walker and Phil Jones of England keep a close eye on Diego Costa

His passion and will to win are hallmarks of his game, although he can take things too far at times, and enjoys great success when channelling his aggression appropriately.

A summer away from the glare of the cameras at the Euros could be just what Costa needs to recover the form that saw him light up the Premier League in his first season.

He has learnt his lesson after letting himself go last year and will undoubtedly be keeping more of an eye on his own fitness in the close-season.

Risking aggravating the problem in France could have ensured 2016-17 continued in much the same vein as last term.

Chelsea will hope Costa’s frustration at missing out with Spain this summer will build up before being unleashed in a flurry of goals when we heads back to west London.

Full Spain squad

The boss: Spain's coach Vicente del Bosque looks on

Goalkeepers: Iker Casillas (Porto), David De Gea (Man United), Sergio Rico (Sevilla).

Defenders : Sergio Ramos, Dani Carvajal (both Real Madrid), Gerard Piqué, Jordi Alba, Marc Bartra (all Barcelona), Cesar Azpilicueta (Chelsea), Mikel San José (Athletic Club), Juanfran (Atletico).

Midfielders: Bruno (Villarreal), Sergio Busquets, Andres Iniesta (both Barcelona), Thiago (Bayern), Isco (Real Madrid), David Silva (Manchester City), Pedro, Cesc Fabregas (both Chelsea), Saúl, Koke (both Atletico).

Forwards: Aritz Aduriz (Athletic), Nolito (Celta Vigo), Alvaro Morata (Juventus), Lucas Vázquez (Madrid).

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