Cristiano Ronaldo's record-setting sixth World Cup began with frustration rather than celebration as Portugal were held to a surprising 1-1 draw by Congo on Wednesday, while the African side marked its long-awaited return to soccer's biggest stage with a historic result.

Portugal arrived at NRG Stadium as overwhelming favorites, backed by a crowd of 68,777 that was largely dressed in red and green. Yet it was Congo that left with one of the tournament's most memorable early stories, earning the nation's first-ever World Cup point and scoring its first goal on the global stage.

The result continued an encouraging start for African nations at the tournament after Cape Verde opened its campaign with a scoreless draw against Spain earlier in the week.

"The World Cup is a tournament where this happens," Portugal coach Roberto Martinez said. "At times the performance is not up to the challenge."

Portugal appeared to be in complete control early.