It was United's game in hand on Arsenal and they did not waste it, while Chelsea drew 4-4 at Tottenham on what turned out to be an excellent night for Sir Alex Ferguson's team.
At one point in the season Bolton had ascended to 13th in the Premier League table but they now appear to be in deep trouble, third from bottom and with games against Arsenal and Chelsea among their remaining eight fixtures.
Trotters boss Gary Megson, without injured skipper Kevin Nolan, might have been encouraged when he saw the United team sheet.
Ferguson left Wayne Rooney on the bench while Rio Ferdinand and Ryan Giggs were rested completely as part of seven changes from the team that won at Derby.
But any hope Bolton had of a positive result dissolved when Ronaldo struck after eight minutes.
Poor control from Abdoulaye Meite gifted possession to United and within seconds Carlos Tevez appeared to be clean through after controlling a cross from Louis Saha with his chest.
It was a slightly heavy touch from the Argentine, allowing Ricardo Gardner to make a decent covering tackle, but after Bolton failed to clear the subsequent corner Ronaldo struck the ball into the floor and up into the opposition goal.
Bolton had set out with five across midfield - and a plan to frustrate their superior opponents, but within 20 minutes that hope lay in tatters.
A disappointing evening for Meite, which ended when he was withdrawn at the break, continued when his foul on Ronaldo was punished in brilliant fashion by the Portugal international.
His strike from a central position 25 yards from goal swerved and dipped at the last moment, leaving Al Habsi helpless.
It was Ronaldo's 24th Premier League goal of the season - taking him four clear of Fernando Torres at the top of the scoring table.
It was also his 33rd goal of the campaign in all competitions - and takes him past the season record set by George Best in 1968 of 32 goals by a winger.
The match might have been different had Davies managed to convert an excellent cross from Danny Guthrie with the score at 1-0 but his cushioned volley was well saved.
Nemanja Vidic, Nani and Tevez all threatened before the break as United looked to exorcise the ghosts of the 1-0 defeat at the Reebok in December.
And Nani came close to a third seconds after the restart, only an excellent low save by Al Habsi stopping his free-kick.
To their credit, Bolton refused to be cowed and enjoyed an excellent period of play.
Kuszczak made an excellent save to tip over a long-range strike from Nicky Hunt and the United keeper followed that with a low dive to thwart Gavin McCann.
El-Hadji Diouf had the ball in the net from a free-kick but the goal was ruled out as the referee had not blown for him to take it.
United continued to pose a goal threat and Al Habsi did well to prevent Ronaldo completing his hat-trick.
Bu the last good chance fell to Bolton's Matthew Taylor with four minutes remaining.
The ball dropped invitingly six yards from goal but his contact was poor and Kuszczak saved.
Man Utd: Kuszczak, Hargreaves, Pique, Vidic (Brown 58), O'Shea, Ronaldo, Fletcher, Anderson (Scholes 70), Nani, Saha (Rooney 70), Tevez. Subs Not Used: Foster, Evra.
Goals: Ronaldo 9, 19.
Bolton: Al Habsi, Steinsson, Meite (Hunt 46), Andrew O'Brien, Gardner, Diouf, McCann, Guthrie (Giannakopoulos 82), Joey O'Brien, Taylor, Davies. Subs Not Used: Walker, Campo, Rasiak.
Booked: Andrew O'Brien, Steinsson.
Ref: Alan Wiley (Staffordshire).
BBC Sport Player Rater man of the match: Manchester United's Cristiano Ronaldo on 9.36 (on 90 minutes).
Please note that you can still give the players marks out of 10 on BBC Sport's Player Rater after the match has finished.
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