The chances of the axe falling on Aberdeen manager Alex Miller increased as his side slumped to a heavy defeat at Rugby Park.

Miller's position has been the subject of intense speculation and there was no sign of the pressure being lifted as Kilmarnock underlined their title credentials.

The Dons fell behind in the sixth minute when Ally Mitchell benefitted from a lucky rebound but after that they made life difficult for themselves with some woeful defending.

Mitchell struck his second after 34 minutes and Jerome Vareille and Paul Wright rounded off the scoring as Killie moved level on points with league leaders Rangers.

Miller recalled transfer-listed John Inglis in a vain bid to bolster his struggling defence with summer capture Mark Perry making way. He also demoted Mike Newell to the bench and gave youngster Dennis Wyness a rare start in attack.

Aberdeen might have gone ahead in the opening minute when Eoin Jess' flick released Robbie Winters on the right, but his angled drive was beaten away by Gordon Marshall.

Kilmarnock's response was swift as Gus MacPherson picked out Wright in the box. The striker mishit his effort but the ball spun over the head of Jim Leighton and against the bar before the rebound fell kindly for Mitchell to nod home.

Ian Durrant fired narrowly wide from distance with a first-time strike that had veteran Leighton scrambling to cover, but Nigel Pepper might have done better for Aberdeen after 27 minutes from David Rowson's through ball.

Pepper needed treatment on the half-hour after being struck by a powerful Mark Reilly shot and Mitchell made it 2-0 from Vareille's square ball.

Kilmarnock went further ahead after 38 minutes when Inglis lost possession and Durrant set up Vareille, who clipped the ball over the advancing Leighton.

Aberdeen took off the ineffectual Wyness at half-time but the introduction of Russell Anderson had little effect.

MacPherson volleyed just wide of the mark from 25 yards as Killie continued to press and Mitchell's industry worked a good position for Durrant on the hour, but Leighton was equal to a well-struck shot from the former Rangers man.

It was only a temporary reprieve and Wright converted a 66th minute spot-kick after Winters was penalised for a needless push on Holt following a deep cross from MacPherson.

Home 'keeper Marshall presented Winters with a chance to redeem himself when he mis-kicked a clearance but the striker somehow scooped his effort over an open goal.

The question now is whether the Aberdeen board will keep patience with Miller who after a year in charge has been unable to halt the troubled club's flirtation with relegation.

He remains confident of his ability to turn things round, saying: "We have money to invest and we are trying to do that. I don't think there was a lack of fight from us, but there is no confidence in the team at the moment."

Kilmarnock: Marshall, MacPherson, Montgomerie, McGowne, Reilly, Holt, Wright, Durrant, Mitchell, Vareille, Baker. Subs: McCoist, Mahood, Roberts, Bagan, Strain.

Aberdeen: Leighton, Whyte, Pepper, Inglis, Smith, Jess, Dow, Buchan, Rowson, Wyness, Winters. Subs: Newell, Stillie, Anderson, Hart, Good.