Atletico Madrid midfielder Koke said his team had "paid for mistakes" as they lost 3-1 on the night at Sevilla to crash out of the Copa del Rey 5-2 on aggregate at the quarterfinal stage.
Atletico looked in deep trouble within 24 seconds when Sevilla left-back Sergio Escudero volleyed in a cross for 3-1 on aggregate, but before the quarter-hour they had equalised on the night when Antoine Griezmann hooked a superb 25-yard lob over goalkeeper Sergio Rico.
Kevin Gameiro and Griezmann had chances before half-time as Atletico pressed to even up the tie, but Sevilla went 4-2 ahead on aggregate just 60 seconds after the break when Ever Banega calmly slotted home a penalty awarded for a foul by Saul Niguez on Rafael Correa.
Simeone's side had most of the ball thereafter, and Angel Correa missed their best chance to get one back, before Sevilla winger Pablo Sarabia put the tie beyond all doubt with 10 minutes left.
Speaking on BeIN Sports after the final whistle, Koke admitted that Sevilla had been the better team, especially in the tie's decisive moments.
"It is a hard blow," Koke said. "We really wanted to do well in this Copa, especially with the final in our new stadium. We did not play a good tie, they were the better team, and we must congratulate them.
"They were better in the decisive moments, we made two mistakes in the first leg, and then at the start today.
"We got back into it at 1-1, and then had another blow early in the second half. It is difficult and even more strange [when you concede five goals in the two games]. But they were better and that's it."
The Copa exit caps a week in which Atletico also dropped two points at home to Girona in La Liga, making their two objectives for this season now a top four finish and the Europa League.
"We had been on a good run, although in these last three games we have not been good," Koke admitted. "But we will have to pick ourselves up, and this team always does that.
"We have to look at all the mistakes we made and improve as we are still up there in La Liga and the Europa League has given us a lot [before]."
The Copa elimination follows Atletico's unexpected Champions League group exit last autumn, and means that the Europa League is now their only realistic hope of silverware this season.
"The responsibility of this exit, and the Champions League, is fully mine," Rojiblanco coach Diego Simeone told the postmatch news conference. "And the responsibility to keep working the same as always. Now we must improve as there are still four months of the season left. I know this group, which keeps me relaxed. We will keep competing as we always have."