The team announced Friday that Matt Cassel will start at quarterback for Sunday's game against Pittsburgh in London, although Ponder said the switch was based on his fractured rib -- as opposed to his performance -- and that he will be back as soon as possible.
"They just made a decision for what's best for me and my health and this team," Ponder said, according to the Minneapolis Star Tribune. "It stinks but it is what it is. But I'll be back for Carolina [after next week's bye]."
Both the Vikings and Steelers are 0-3.
Ponder had a CT scan on his chest Monday, which revealed the fracture. He said the broken rib is near his heart, causing the doctors concern about him playing Sunday.
Cassel, the former backup at USC who went on to replace the injured Tom Brady for a season at New England before becoming the regular starter in Kansas City, said he found out Friday that he would be making his first start for the Vikings.
"I've been through a lot," he said. "But at the same time, you get those butterflies."