Spain head coach Julen Lopetegui admitted it was "painful" to leave Alvaro Morata out of his World Cup squad.
The Chelsea striker was overlooked for the final 23-man group for the tournament in Russia, which was announced on Monday.
Morata scored five goals in as many appearances during the qualifying campaign but his struggle for form and fitness in the Premier League this season left him facing a battle to keep his place for the finals.
Lopetegui found the decision difficult but said he did not want to take four players for the centre-forward role, with Diego Costa, Rodrigo Moreno and Iago Aspas the preferred options.
"They are tough moments for a player. It's not nice, he deserved to be here," Lopetegui told a news conference.
"I have the important opinion and it's painful, but I've made the decision.
"I've spoken with those I had to speak to, I'm not going to name anybody. I've had various doubts. To make a list of 23 is a difficult decision.
"We've opted for three other team-mates who have other conditions. Taking four players in that position is not something we wanted to do. It's a footballing decision.
"It's the most bitter taste to leave someone out. They deserve to be there but they couldn't get in. They helped us and they cannot be here. We have chosen those who can help us the most in this amazing adventure.
"Iago can play centrally and out wide, Rodrigo can play in three areas and always has a great attitude with the team. Diego Costa brings a lot of competitiveness."
|Hopoate handed 10-year ban from NSWRL|
|Is this worth it? Injuries prompted Te´o to consider future|
|Croatia hero Subasic retires from international football|
|Iniesta makes it two in two for Vissel Kobe|
|Chelsea send out defensive duo on loan|
|Zaha 2023: Palace star means more than goals|
|De Jong set for Ajax stay despite Barcelona interest|
|Serena ´still at the very beginning´ of comeback|
|Ajax can benefit from Mourinho approach - Blind|
|Foley not convinced by reports All Blacks will drop Barrett|
|Zaha signs Crystal Palace extension|
|Burnley midfielder O´Neill makes A-League loan move|
|Godin yet to renew with Atletico Madrid amid transfer interest|
|Federer ´feeling better every day´ after Wimbledon disappointment|
|Kante comfortable with surprise new Chelsea role|
|Rugby Championship 2018: The numbers behind New Zealand´s dominance|
|LaLiga 2018-19: Bale ready to be Madrid´s shining light after five years in Ronaldo´s shadow|
|Rodgers unimpressed by absence of ´fit´ Boyata|
|Braves´ Acuna Jr. has arrived as a true MLB star|
|LA Galaxy 2 Colorado Rapids 2: Jackson´s deflected strike sees spoils shared|
|Victory offer postponed retirement, says Honda|
|Kyrgios forgets tennis shoes, Federer back in business|
|Williams knocked out as Garcia and Pliskova advance in Ohio|
|Kvitova sees off Serena in Cincinnati classic|
|Federer dispatches Gojowczyk in Cincinnati|
|Stead succeeds Hesson as New Zealand coach|
|Duminy encouraged despite South Africa´s mixed results|
|Thiem withdraws from Cincinnati Masters|
|Edwards joins Ospreys in consultancy role|
|Former Arsenal and Barcelona player Song joins Sion|
|I´m very happy with what I have - Spalletti not desperate for Modric|
|Roethlisberger evaluated for concussion after practice|
|Brady ´absolutely´ expects to face Eagles|
|Rugby Championship 2018: Reasons for optimism and concern for Australia|
|Wentz ´gonna be close´ for Eagles opener|
|Cleveland ´victory fridges´ to unlock beer if Browns finally win|
|England´s Watson suffers injury setback|
|Mariners reinstate Cano after 80-game suspension|
|AEK Athens 2 Celtic 1 (3-2 agg): Rodgers´ men dumped out of Champions League|
|Alonso to leave F1: Paddock reacts to Spaniard´s exit|
|Roma sign midfielder N´Zonzi from Sevilla|
|Alonso to leave F1: Who will replace Fernando at McLaren?|
|Extraordinary Zidane is in Real Madrid´s past - Lopetegui|
|Alonso to leave F1: Then and now - how the grid, teams and calendar have changed since 2001|
|Wawrinka and Azarenka receive US Open wildcards|
|Parma sign Napoli pair Inglese and Grassi on loan|
|Sandakan castles Proteas before Sri Lanka squeeze home|
|Ronaldo sale won´t stop Real Madrid winning - Ramos|
|Predators sign Ryan Ellis to eight-year, $50M contract|
|Curran, Woakes, Rashid - who makes way for Stokes in England´s Test XI?|
|Griezmann well positioned for Ballon d´Or, says Simeone|
|Criscito: I was on Genoa bridge shortly before collapse|
|Alonso to leave F1: How the Spaniard´s numbers stack up to the greats|
|Rookie LB Roquan Smith finally signs Bears contract|
|De Villiers enjoying relief from ´unbearable´ Proteas pressure|
|Fernando Alonso to leave F1|
|Spalletti extends Inter contract|
|Godin, Koke, Griezmann and Juanfran named Atletico Madrid captains|
|Ronaldo out of hospital after illness|
|Fury: Beating Wilder and Joshua ´very easy´|
|Dickinson retires to take up academy coaching role|
|Cricket the ´sole focus´ for Stokes as he returns to England squad|
|Cheryshev moves to Valencia on loan|
|Mandzukic retires from Croatia duty after World Cup|
|Ben Stokes found not guilty of affray|
|Tottenham issue new stadium update and apology to fans|
|Chelsea flop Bakayoko moves to AC Milan on loan|
|Gabi urges Al Sadd team-mate Xavi to play on|
|Ronaldo leads UEFA Goal of the Season nominees|
|Federer: Djokovic could be caught up in US Open pressure|