Luis Enrique said Spain lacked "finesse" during their "uninspiring" 1-1 draw with Greece, while admitting "it is a result I did not expect".
Spain were held at home in their opening 2022 World Cup qualifier on Thursday night, with an Anastasios Bakasetas penalty cancelling out Alvaro Morata's stunning opener.
Enrique was left frustrated by his team's failure to carve out clear-cut openings after heading into the game confident of victory.
What's been said?
"Against a retreating rival like Greece that has a strong physical level and that defensive precision we have lacked finesse," the La Roja boss told reporters.
"With so little space [against that defence] we have been uninspiring. Obviously it is a result that I did not expect.
Next Match
"We have not generated the flow of chances to be able to score more goals. My job is to try to help the players.
"You have to try to solve the games against all the rivals. Greece has come to play their game.
"Every game has its complications and today Greece defended very well."
Why was Sergio Ramos substituted at half-time?
More than a few eyebrows were raised when Enrique decided to bring off Spain captain Ramos at the interval, with Inigo Martinez introduced as his replacement in the heart of the defence.
Ramos picked up a slight knock to his knee during Real Madrid's last La Liga outing, and Enrique said it was pre-arranged for him to come off early in the Group B fixture.
"He was perfectly fit to play," he said. "But we had already talked and we decided that he would only play the first part [of the match]."
Spain's road to Qatar 2022 begins with a whimper
Spain were heavy favourites before kick-off against Greece, but struggled to find a route to goal in the first half hour of the game as their opponents sat back and waited for opportunities to counter.
Dani Olmo came closest for the hosts when his shot cannoned off the bar before Morata finally made the breakthrough in the 33rd minute, producing an outstanding volleyed finish to take his overall tally of goals in World Cup qualifiers to six.
Greece were not to be denied, though, with Ramos' replacement Martinez punished for a late foul in the box shortly after half-time which gave Anastasios Bakasetas the chance to score from 12 yards.
Bakasetas made no mistake from the penalty spot and the visitors held on for a valuable point thereafter, with Morata guilty of missing a free header late on.
What's next?
Spain will now look ahead to a meeting with Georgia on Sunday, which comes three days before they are due to play host to Kosovo.