The Newcastle United striker put aside the frustration of his injury-hit first season with the Premier League club as he headed home to secure a 1-1 draw under a closed roof in Houston on Wednesday (Thursday AEST).
Joao Neves had put Portugal, one of the pre-tournament favourites, ahead after just six minutes but they were unable to build on their strong start as DR Congo – making their first World Cup appearance in 52 years – fought back in the Group K opener.
Ronaldo, matching Lionel Messi's feat of appearing at a sixth World Cup, didn't have the same sort of sensational impact that his old Argentine rival had enjoyed the previous night with his hat-trick against Algeria, as 'CR7' failed to convert two difficult late chances after a quiet game.
Portugal's superstar didn't speak to reporters after the game, but posted about the match on X.
"It wasn't the start we wanted, but this is far from over," he wrote.
"Head up and focus on the next game."
The African side sat deep early on and were punished as Portugal controlled possession and soon created the opening goal.
Pedro Neto found space down the left and whipped in a cross for Neves to rise and power a header into the top corner.
The Leopards responded with Wissa and Cedric Bakambu threatening.
On the day it was announced he had signed for Real Madrid, Portugal's Bernardo Silva was booked for a poor challenge on Edo Kayembe, before Bruno Fernandes drove a cross through the box and both Neto and Joao Cancelo failed to pick out Ronaldo.
DR Congo finished the first half strongly and drew level in added time.
A short corner was worked to Arthur Masuaku and he swung a ball in for Wissa to arrive unmarked at the back post and head past Diogo Costa.
Portugal thought they had reclaimed the lead 10 minutes into the second half after a brilliant overhead kick from Cancelo, but the former Manchester City defender was offside.
The Europeans looked to Ronaldo for inspiration, but he twice missed the target from Francisco Conceicao cutbacks before Bakambu shot wide as DR Congo held on for a surprise point.
Portugal coach Roberto Martinez was asked if he considered substituting Ronaldo.
"It makes no sense to get the best world scorer to be out when you need goals," Martinez said.
"The experience of Cristiano in the box is important. The way that he attracts defenders is important."
With the AP.
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