Steinsson stuns the Riverside crowd with the opening goal
Bolton brought Middlesbrough's unbeaten run of five games to a grinding halt with an easy win at the Riverside.
Iceland's Gretar Steinsson nodded in Matt Taylor's cross for the opener via the head of team-mate Kevin Davies.
Taylor then doubled the lead, cleverly wrong-footing the defence before firing in Steinsson's pass from the right.
Emanuel Pogatetz pulled one back in the second half, but Swedish international Johan Elmander crashed in the third to wrap up the game for the visitors.
Bolton had only scored three times in six league games before the match, and were not fancied to add many to their tally with the hosts on a great run since their 5-0 demolition by Chelsea a month ago.
Davies praises 'perfect performance'
But the minds of Boro's defenders seemed to be still in the changing room as Taylor whipped in a dangerous cross from the right after just eight minutes.
Steinsson, lurking on the back post, nodded towards goal and the ball flew into the top right hand corner after deflecting off the back of Davies's head.
Middlesbrough were shocked and two minutes later Ross Turnbull was picking the ball out of the net again.
This time it was Steinsson's turn to play provider, picking out Taylor as he darted towards the penalty spot.
A deft touch with his left foot enabled Taylor to out-fox Middlesbrough's defenders and gave him the space and time to pick his spot and bury the ball in off the left post.
It was a fantastic start to the game and Boro went close to an immediate reply when Gary O'Neill's volley was cleared off the line by Kevin Nolan.
Gareth Southgate's team began to wake up, but despite the lively Afonso Alves and Tuncay proving a handful, Bolton's energy and commitment kept them in front.
Boro were awarded two free-kicks early in the second half, but Alves blasted both into the stands and it looked as if it would not be their day.
Southgate hopes for a return to form
After Fabrice Muamba dragged a one-on-one wide of the left post for Bolton, the home fans finally had something to warm themselves up as the snow began to fall.
A goalmouth scramble led to David Wheater hooking the ball back in towards Pogatetz, who fired into the roof of the net to reduce the deficit.
It was game on, but the visitors stormed back up to the other end and just 63 seconds after Middlesbrough's goal, record signing Elmander crashed the ball home at the other end for only his second of the season.
Middlesbrough kept pressing, but with Stewart Downing disappointingly anonymous after his efforts for England against Germany, they were unable to break down a very stubborn defence.
Bolton boss Gary Megson:
"We got a terrific start but we didn't press it home and we were looking to hang onto it instead of pushing forward. We are a bit of an enigma at the moment.
"We spoke at half-time about having that little bit of belief and that will come from myself and the staff and everyone connected with the club. They need a bit of help to believe in themselves."
Middlesbrough manager Gareth Southgate:
"We did not play well enough to get anything out of the game and they deserved the points.
"We made the wrong decision with and without the ball and we were punished. We let ourselves down and we've learnt a harsh lesson.
"We have had a good run but it had to come to an end at some point and now we have to bounce back against Newcastle."
Middlesbrough: Turnbull, Hoyte, Wheater, Pogatetz, Taylor (Arca 76), Aliadiere (Adam Johnson 58), O'Neil, Digard, Downing, Alves (Emnes 75), Sanli.
Subs Not Used: Jones, Hines, Grounds, Walker.
Booked: Pogatetz, Digard.
Goals: Pogatetz 77.
Bolton: Jaaskelainen, Steinsson, Cahill, Andrew O'Brien, Samuel, Taylor (Gardner 89), McCann, Muamba, Nolan, Elmander (Smolarek 84), Davies.
Subs Not Used: Al Habsi, Riga, Shittu, Basham, Obadeyi.
Booked: Muamba, Cahill, Samuel, Nolan, McCann.
Goals: Steinsson 8, Taylor 10, Elmander 78.
Ref: Martin Atkinson (W Yorkshire).
BBC Sport Player Rater man of the match on 90 minutes: Bolton's Gretar Steinsson - 7.77 (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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