Bolton piled the pressure on troubled West Ham with a comprehensive victory.
Davies (right) opens the scoring for Bolton
Kevin Davies opened the scoring with a close-range volley after El-Hadji Diouf had knocked the ball across the box.
Davies poked home his second from a corner after the break before Diouf bewitched two defenders and drove in precisely to make it three.
Nicolas Anelka completed the rout when he dinked the ball over Robert Green after collecting Gary Speed's pass, before Ivan Campo hit the post late on.
It was a fitting moment for Speed, who was typically impressive in his record-breaking 500th Premiership appearance.
But it was a damning verdict on a West Ham side desperately short of ideas.
The closest they came to breaking their goal drought was a second-half Marlon Harewood shot.
Neither side went into the game on a good run, with Bolton having managed just one win in seven league games and West Ham had lost four of their last five.
So it was unsurprising that there was hesitation in most of the play and a lack of confidence all round.
It was Bolton who shook off their shackles more easily and particularly in the shape of Anelka, they began to threaten.
And when the Frenchman picked up the ball and embarked on a solo run, he could sense there was something on.
His deep cross found Speed, who the ball was nodded back across goal and Diouf was on hand to hook the ball towards Davies, who lashed in a volley.
Bolton then settled into an easy rhythm with Campo dictating the play in midfield, where there seemed an absence of West Ham players.
The visitors also lacked a presence up front and managed only one first-half effort on goal - a feeble shot from Carlos Tevez on 44 minutes, which barely had the pace to reach the keeper.
Before that, West Ham could have found themselves further behind when they failed to properly mark Diouf, but the striker headed down and wide.
After the break, the teams quickly assumed their roles once more.
And Bolton doubled their lead on 52 minutes when Campo headed the ball on and Davies reacted fastest to divert the ball home.
In a rare Hammers' offensive, Harewood fashioned a chance to reduce the deficit but his finish did not match his smart turn and he drove the ball across the face of goal.
West Ham were then fortunate as Diouf suffered a lapse of concentration when well placed in the area, losing control of the ball when he seemed set to score.
But Diouf showed his ability on 77 minutes, when he danced his way past two defenders before prodding the ball into the corner.
And a minute later, Speed's excellent pass released Anelka, who showed tremendous pace and poise to take the ball in his stride and finish expertly.
It was almost five for Bolton when Campo worked an opening but he saw his shot crash back off the foot of the post.
Bolton manager Sam Allardyce:
"I'm absolutely delighted because we'd lost two games and we've found goals difficult to come by.
"To get four today, with the front three all scoring, was terrific. It wasn't as easy as it looked, West Ham put up a good fight.
"Our finishing was high quality and it's a big victory. Hopefully it gives us the confidence to go on a run."
West Ham boss Alan Pardew:
"Bolton were very very good, unfortunately we were the opposite. We were very stretched at the back.
"We battled hard and tried to play - sometimes we overplayed. But, having said that, this was a fair result.
"We are going to need some strong characters to bounce back after this result - we are in a tight spot. As a team we were not good enough today."
Bolton: Jaaskelainen, Hunt, Faye, Meite, Pedersen, Campo, Davies (Vaz Te 82), Nolan, Speed (Gardner 88), Diouf (Tal 79), Anelka.
Subs Not Used: Al Habsi, Giannakopoulos.
Booked: Diouf, Campo.
Goals: Davies 17, 52, Diouf 77, Anelka 78.
West Ham: Green, Spector (Pantsil 61), McCartney, Dailly, Collins, Konchesky, Mullins, Reo-Coker, Etherington, Harewood, Tevez (Sheringham 61).
Subs Not Used: Carroll, Zamora, Benayoun.
Booked: Reo-Coker, Etherington.
Ref: H Webb (S Yorkshire).