Ruud van Nistelrooy tapped home his 150th Manchester United goal to blast the title door wide open.

Left on the bench again for the crucial clash with Bolton, Van Nistelrooy was introduced on the hour mark of a pulsating local derby and promptly scored the goal that not only put his name into the Red Devils' history books but left stumbling Chelsea looking fearfully over their shoulders.

In becoming the eighth United player to hit the landmark, Van Nistelrooy reduced Chelsea's lead at the top to seven points and Jose Mourinho will not need reminding Sir Alex Ferguson's rampant side have still to visit Stamford Bridge.

How ironic too that Van Nistelrooy's effort - which sealed an eighth straight Premiership win for the Red Devils - should be set up by Louis Saha, the man who has taken the Dutchman's place in Ferguson's first choice line-up.

As the pair jubilantly embraced 11 minutes from time, there was no hint of bad feeling. After all, both will profit if United can keep their present run going.

At one stage not so long ago, Chelsea were 18 points clear and Mourinho was confidently talking of wrapping up the title by Easter.

As it currently stands, the Portuguese boss will probably be delighted to take back-to-back championships any way they come.

After all, it is only 10 years since United hauled back Newcastle from a similar deficit and their current charge shows no sign of slowing.

Having given the impression he thought Chelsea's visit to Birmingham was 24 hours later than it actually was, Ferguson must have been both surprised and delighted to learn Mourinho's men had suffered another unexpected stumble on what was supposed to be a clear path to their destiny.

By the time news of Chelsea's draw had filtered through, Ferguson had already decided to axe Van Nistelrooy in favour of Saha, preferring the Frenchman's extra physical presence against one of the Premiership's most robust teams.

And how Saha justified the move. Aside from his clinically executed goal and his crucial assist, the former Fulham man was a constant menace to the normally all-powerful Bolton defence.

Saha's speed and strength kept the Trotters at full stretch throughout and the only major disappointment for United must have been that his 14th strike of the season only brought them level.

Wayne Rooney in particular must have wondered how he had not managed to get his nae on the scoresheet.

The brilliant England man has been below par by his own monumentally high standards in recent times but the 10th-minute chance that passed him by still took some explaining.

Saha showed supreme awareness to let Ronaldo's dangerous cross run on to Rooney, who, totally unmarked by the penalty spot, had the goal at his mercy.

What happened next almost required a second take as Rooney found a first touch so poor it would have embarrassed a Conference forward as he succeeded only in bouncing the ball straight into the arms of a grateful Jussi Jaaskelainen.

The Finn was required to do far more when United next pressed forward as Gary Neville's cross was half cleared to Ryan Giggs.

Jaaskelainen proved equal to the Welshman's effort and then denied Rooney, who strode up to the rebound with confidence, only to turn away in disgust at yet another failure.

Rio Ferdinand and Cristiano Ronaldo both wasted chances, so they only had themselves to blame when Kevin Davies put the hosts in front.

Abdoulaye Faye set the move in motion by winning an aerial duel with Nemanja Vidic. Kevin Nolan then threaded a pass to Kevin Davies, who instantly pushed the ball through Ferdinand's legs, darted into the box and beat Edwin van der Sar with ease.

At similar times this season, at Middlesbrough, Manchester City and Blackburn, United have crumbled. Not today.

When Bruno N'Gotty and Joey O'Brien got their wires crossed trying to play offside as United pushed forward, Saha seized Silvestre's pass and beat Jaaskelainen with a brilliant first-time effort.

Van Nistelrooy's introduction after 15 second-half minutes of nothing much proved the catalyst for yet another United win.

The Dutchman had already seen a couple of chances go begging, with Saha wasting an even better one, before his striking rival raced onto John O'Shea's through ball and cut the pass back for Van Nistelrooy to tap home.

Teams

Bolton Jaaskelainen, O'Brien (Hunt 74), Ben Haim, N'Gotty,Pedersen, Faye, Nolan, Okocha, Speed (Diouf 87),Giannakopoulos, Davies (Borgetti 87).

Subs Not Used: Al Habsi, Nakata.

Booked: Faye.

Goals: Davies 26.

Man Utd Van der Sar, Neville, Ferdinand, Vidic, Silvestre,Ronaldo (Park 90), O'Shea, Giggs, Fletcher (van Nistelrooy 61),Rooney, Saha.

Subs Not Used: Howard, Evra, Pique.

Booked: Ronaldo, Rooney.

Goals: Saha 33, van Nistelrooy 79.

Att: 27,718

Ref: A Wiley (Staffordshire).