Bafana suffered a 2-0 loss to the tournament co-hosts in their Group A opener at the Azteca Stadium, leaving them under pressure ahead of a crucial clash against Czechia.
Despite the setback, Sibisi remains confident South Africa can recover.
"We know what we have to do. We have to go back, analyse and recover so that we can be as fresh as possible for the next game," Sibisi told SABC Sport.
"The opportunity is still there, so not all is lost, and I think we saw some glimpses of what we can do, but it just wasn't enough."
The Orlando Pirates captain felt South Africa's display was undermined by a lack of quality in the final third rather than a poor overall performance.
"We are very disappointed with the result, but I don't think it was a bad game from our side," he said.
"It was just the final ball whenever we were attacking that was lacking."
While Bafana struggled for goals, Mbokazi emerged with plenty of credit after an assured defensive performance against Mexico.
The 20-year-old Chicago Fire centre-back has impressed during his first season in Major League Soccer and carried that form onto the World Cup stage.
Sibisi, who played alongside Mbokazi at Orlando Pirates, said the youngster's success comes as no surprise.
"When you talk about Mbekezeli, such a humble soul. I recall my very first encounter with him, when he was still playing in our development ranks. From there, I took him under my wing. I could see the potential he had and the person he was," Sibisi said in the documentary On the Rise: From South Africa to Chicago Fire.
"Coming from the same neighbourhood and the same province, I knew from the start that he was going to be something big - but he had to prove himself, and within a short space of time, he did that.
"I've been following some of his games in Chicago; he's settling in quite well, and I'm very proud of him."
Sibisi believes Mbokazi's confidence is one of his biggest strengths.
"One of his big attributes is his confidence and his ability not to be afraid regardless of the stage."
South Africa now head into a must-win meeting with Czechia, knowing defeat could bring an early end to their World Cup campaign.
