Amad Diallo struck in the 90th minute to give the Ivorians all three points in their Group E clash after Ecuador had dominated long spells of the game, hit the woodwork three times and squandered several clear opportunities.
"It hurts because it was an unfair defeat," Beccacece told reporters.
"I think there are very strong arguments to clearly show that the team competed very well, had the clearest chances and could have won the match, but because of one detail at the end, we leave with nothing."
Ecuador arrived at the tournament unbeaten since September 2024 and boasting one of the strongest defensive records in international football, but were punished for their inability to turn first-half dominance into goals.
"When a team is clearly superior and doesn't take its chances, it gives the opponent the feeling that it is still alive," Beccacece said.
"I never felt they deserved to win the match, but football is not about what you deserve. It's about taking your chances."
The Argentine coach was also unhappy with a second-half foul by Ivory Coast defender Guela Doue.
"We all saw what was clearly a second yellow card and a sending-off," Beccacece said. "Those are things we cannot control. They hurt, but we have to accept them."
Response key for El Tri
Beccacece insisted Ecuador's hopes of reaching the knockout stages remained firmly in their own hands ahead of matches against Curacao and Germany.
"When you don't start the way you wanted, the anxiety appears," he said.
"But now we need more conviction than ever, more belief than ever, more confidence than ever."
The coach praised Ecuador's supporters, who turned Philadelphia into a sea of yellow throughout the evening.
"What hurts me the most and makes me the saddest is not being able to give something back to the people," he said.
"When you do enough to win, with the atmosphere that was created here, and you don't achieve it, it hurts."
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The 2026 World Cup will be held from June 11th to July 19th in the United States, Canada and Mexico. The tournament will feature 48 national teams and will be played in 16 modern stadiums.
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