A spirited second-half display went unrewarded as City began the New Year with a narrow defeat in East London.
Hosts Millwall dominated the first half and should have led by more than the single goal afforded to them by Dany N’Guessan after 19 minutes.
But City were transformed after the interval, and deservedly levelled through Jon Stead before full-back Adam Smith struck a rare goal with a sweet volley 15 minutes from time to win the day.
Derek McInnes made two changes to his side victorious at home for the first time since August against Peterborough United last time out.
Instead he reverted to the 5-4-1 formation effective at Ipswich in City’s last assignment on the road, as Sam Baldock made way for Liam Fontaine with McInnes seeking greater stability against the play-off hopefuls
Elsewhere, Mark Wilson replaced Richard Foster, who limped out of Saturday’s win with a hamstring injury, in the right wing-back position.
It was the hosts who began with greater purpose. In the very first minute, Liam Feeney crossed from the left for Darius Henderson – so prolific against City in years gone by – only for the striker’s header to drift inches wide of Tom Heaton’s far post.
It was a rude awakening for the Robins, who had to deal with a number of crosses into the box in the opening exchanges.
City were struggling to find sustained possession, and an unfortunate diversion off Albert Adomah
’s nether regions inadvertently started a Millwall attack, allowing midfield powerhouse Liam Trotter to break away and see his well-placed shot just turned around the post by a fine Heaton save low to his left.
But the reprieve was short lived, as City fell behind on 19 minutes to N’Guessan’s first goal of the season. Only playing in the absence of departed loanee Chris Wood, the striker neatly sidestepped Matthew Bates and cracked a low left-footed shot across Heaton to break the deadlock.
The hosts were in complete control, but chances were not proving easy to come by until the final ten minutes of the half. First Trotter glanced wide from Smith’s right-wing cross, before defender Mark Beevers was within a whisker of doubling the lead from a James Henry corner.
McInnes’ concern was clear and moments before the interval the manager made a double switch. Fontaine and Paul Anderson were sacrificed, with Martyn Woolford and Baldock introduced as City reverted to 4-4-2.
It had been a sorry half for the visitors, who survived a late N’Guessan half-chance to escape at the interval only a solitary goal worse off than the dominant Lions.
No doubt McInnes would have had a few choice words for his players, before City began the second half with the best attack of the game.
Twice the ball was played wide to Woolford on the left, before Adomah found Danns in a shooting position on the edge of the box. The midfielder let fly with City’s first attempt of the game high towards the near post, with Millwall keeper David Forde having to divert it into the sidenetting with the slightest of fingertip touches.
Suddenly the game was a real contest and the two substitutes were making a difference. Baldock neatly let the ball roll across his body before shooting low towards the near post, only for a strong right hand from Forde to turn it behind.
From the resulting corner, Stead set up Woolford who skewed his shot wide. But City’s level of performance had improved immeasurably, and Stead’s first goal since the second league game of the season hauled them level.
After a spout of pinball inside the Millwall penalty area, the ball was lifted back over the defence for the former Ipswich Town striker, who slid in to finish impressively across Forde on the stretch in front of a buoyant travelling contingent.
Having been so poor throughout the first half, it was actually an equaliser which had been coming. City looked hungry for more, but were again indebted to Heaton as the keeper saved well from Trotter and Henry from distance.
An inviting chance to turn the game on its head arrived 17 minutes from time. For the first time all afternoon, Adomah beat Millwall left-back Shane Lowry and crossed from the byeline low towards Baldock, who got across Danny Shittu at the near post but could not make the necessary contact from six yards.
It was to prove a costly miss, as the hosts moved back in front against the run of play just two minutes later.
Henry’s flighted free kick into the City box was headed across goal by Trotter and thundered into the net on the volley by the onrushing Smith ten yards out.
McInnes’ men had every reason to feel aggrieved, having been far the better side since half-time. Heaton again denied Trotter, whose dipping shot was goalbound, before City pressed hard for a late equaliser.
Two minutes from time the ball broke to Adomah eight yards out, but the winger scuffed his shot. With five added minutes signalled by the fourth official, a vocal home crowd were getting restless, but their team held on to secure three vital points.