Gary Cahill celebrates after restoring Bolton's lead
An emphatic second-half display from Bolton left struggling Middlesbrough deeper in the relegation mire.
Gareth Southgate's men cancelled out Kevin Davies' early opener when Tuncay set up Gary O'Neil for a Boro equaliser just before the interval.
But Gary Cahill rapidly restored Bolton's lead from Matthew Taylor's well-flighted free-kick.
And second-half goals from Taylor and Ricardo Gardner consigned Boro to their ninth successive away defeat.
The defeat leaves Gareth Southgate contemplating Boro's worst run of away form since the Second World War. Despite the decisive nature of the scoreline, however, Boro battled determinedly and, with better finishing, might have left the Reebok with more to show for their efforts.
Megson pleased with 'huge' win
Bolton have made a habit of scoring early goals this season and, unbowed by some early Boro pressure, bagged a trademark eighth-minute opener against the run of play.
Gardner, a model of industry and determination along Bolton's left wing all afternoon, sent a precise, floated cross to the far post, where the lurking Davies gratefully claimed his sixth goal in nine outings.
Bolton's breakthrough was the cue for a sustained period of pressure. Within moments, Boro were almost in trouble again when a defensive mix-up between David Wheater and Brad Jones denied the goalkeeper a routine catch.
A Huth error then released Gardner, whose surging run into the area was halted by a superbly-timed intervention from the increasingly-beleaguered Jones, who had turned over a stinging Davies free-kick only minutes earlier.
Having weathered the mid-half storm, however, Boro began to show signs of a resurgence.
Downing brushed the side-netting with a shot from range and Wheater and Huth also came close before Alfonso Alves hit the post with a free-kick.
Something had to give, and when Alves sent a cushioned header into the path of Tuncay - who, moments earlier, had seen a goal chalked off for offside - it finally did.
The Turkey international laid the ball off for Gary O'Neil, and the midfielder steered a composed finish past Jaaskelainen's outstretched glove.
By then, Boro were without their captain, Emanuel Pogatez, who had given way to Andrew Taylor after succumbing to injury.
Perhaps missing the skipper's organisational influence, the Boro defence once again looked less than organised when Bolton won another set-piece three minutes from the interval.
Matthew Taylor floated a free-kick into the penalty box from deep on the right flank, Cahill exchanged passes with Johan Elmander before calmly firing beyond Jones to restore Bolton's lead.
Southgate bemoans poor defensive display
Staring defeat in the face, Boro rallied in determined style after the break but were repeatedly thwarted by a lack of cutting edge. At the heart of their efforts was Tuncay, who sent an acrobatic volley narrowly wide before smashing a volley over.
Bolton were given further cause for concern when Gretar Steinsson's under-hit back-pass gave Alves an excellent chance, snuffed out by Jaaskelainen, to pull level again.
But with 12 minutes remaining, Bolton won another free-kick on Boro's right flank. Taylor once again stepped up, delivering a high, looping ball that eluded the forehead of Huth before bouncing past the hapless Jones.
Gardner completed the rout in the closing minutes when he turned home a cross from Taylor to burnish the win and complete a miserable afternoon for Boro.
Bolton manager Gary Megson on Kevin Davies and the victory:
"It's not just Kevin's goalscoring, it's his honesty and his workrate, he wins a lot of balls and he creates a lot of goals.
"This season he is scoring a lot more than he has done. All we've asked him to do is keep getting in front of goal.
"We had the knowledge that if we could win and the results went how we hoped it would be a huge boost and that's how it turned out."
Middlesbrough manager Gareth Southgate on his side's survival chances:
"We've got to be realistic and we have to beat Hull at home and if we can do that things can turn around.
"But to be able to do that the level of performance must be better than today.
"We've conceded really poor goals today. We looked a threat going forward and created quite a few chances but were poor at the other end."
Bolton: Jaaskelainen, Steinsson, Cahill, Shittu, Samuel, Taylor, Muamba, McCann, Gardner, Elmander (Basham 83), Kevin Davies. Subs Not Used: Al Habsi, Hunt, Smolarek, Puygrenier, Cohen, Andrew O'Brien.
Booked: Shittu, Muamba.
Goals: Kevin Davies 8, Cahill 44, Taylor 78, Gardner 84.
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