Robert Guerrero pulled out of his August 27 WBA super lightweight bout against Marcos Maidana due to a left shoulder injury.

The bout, which has been postponed indefinitely, was to take place at HP Pavilion in San Jose, but now the entire card has been canceled. It was to be shown on HBO.

Guerrero sustained the injury during a sparring session Wednesday afternoon. He was on his way to get an MRI to determine the severity of the injury.

"I'm devastated because I worked my whole life for the opportunity to be a main event on HBO," Guerrero said. "It's a major blow to my team and family."

Guerrero (29-1-1, 18 KOs) was coming off a 12-round unanimous decision over Michael Katsidis in April.

Maidana (30-2, 27 KOs) scored a majority decision over Erik Morales, also on April 9, the same card when Guerrero fought Katsidis in Las Vegas.

"I am very disappointed to hear that Guerrero was injured, especially at this stage of training camp," Maidana said. "I hope he recovers soon, but I also want to get an opponent to replace him because I've been working really hard for about 12 weeks and I need to fight. I'll face whoever they put in front of me next."