Ferguson believes the title race will go to the wire and heaped more praise on his skipper for the night, while opposite number Gary Megson called the winger "the best player in the world".
Ferguson said: "The important thing was that we had the opportunity and the incentive to go three points clear of Arsenal, our nearest pursuers.
"It's a lead, it's not a significant lead but it's a lead nonetheless.
"With eight games to go the team who plays with the most consistency now will win it.
"Ronaldo's free-kick was marvellous. He does put in the practice and he has this technique."
Ronaldo now has 33 goals this season - overtaking George Best's 32 in 1968, the most a United winger had scored in one campaign until now - and 24 in the league.
Ferguson added: "It's fantastic and speaks volumes about the player, it's amazing that he can do that playing in the position he does."
Gary Megson saw some cause for hope in Bolton's fight against relegation after a good second-half display - and admitted his players were still in awe about the quality of Ronaldo's free-kick.
Megson said: "It was genius from probably the best player in the world at the moment.
"Everyone in the dressing room afterwards was talking about how he does it. We have seen him do it twice now and the truth is we just don't know how he does it.
"But for the first goal we caused our own downfall. The marking from the corner was sloppy and when you have that sort of quality against you then you cannot afford to do that.
"If we can replicate our second-half performance then there is optimism.
"We had more shots in this game than probably any away game we have played and we need to keep it going in every game until the end of the season."