Manchester United moved 2nd in the Premiership after Ronadldo struck 5 minutes after half time to give them the lead.
United lost keeper Edwin van der Sar through injury at half-time and had to survive a spirited Birmingham display.
Fortsätt läsa Ronaldo 1 : 0 Birmingham
Sir Alex Ferguson launched a bitter attack on Joe Cole for the tackle he felt should have seen Chelsea reduced to nine men at Old Trafford on sunday.
Chelsea were already a goal and a man down when Cole launched himself at Cristiano Ronaldo during the second half of his side’s 2-0 defeat to Manchester United.
Getting nowhere near the ball, Cole caught Ronaldo crudely on the ankle, but was only booked by referee Mike Dean, a move which triggered a furious reaction from Ferguson, whose mood had not changed after the final whistle.
”Joe Cole should have been sent off,” said the Scot. ”Tackles like that are a danger to players. He went right down the back of his leg and could have done some real damage.
”It is the type of thing Cristiano is facing all the time now, but Cole got off with it because the referee was balancing things out after the first sending-off.”
Fortsätt läsa Ferguson angered by Cole’s tackle on Ronaldo
Everton fan: Man Utd’s Ronaldo left me in excruciating pain
Merseyside Police have confirmed they are speaking to witnesses and studying CCTV to establish precisely what happened during Saturday’s match at Goodison Park when Everton faced Manchester United.
Carl Lloyd, 34, told the Daily Post that the Portuguese winger sank his studs into his right arm.
The joiner alleged the incident happened during the Premier League clash as he leaned over the advertising hoardings to retrieve the ball when it went out of play.
Fortsätt läsa Everton fan: Man Utd’s Ronaldo left me in excruciating pain
Cristiano Ronaldo scored a second-half header on his return to Sporting Lisbon to ensure Manchester United’s Champions League campaign started with a victory.
Ronaldo won warm applause from the home fans for his subdued response to converting Wes Brown’s cross after 61 minutes of a low-key encounter.
Wayne Rooney made a quiet comeback after recovering from a broken foot.
And United were grateful to keeper Edwin van der Sar, who made superb saves from Liedson and Tonel.
Fortsätt läsa Ronaldo scores against former club