A dominant second-half performance eased Bristol City past Millwall at The Den, with a 3-0 win securing their place in the fifth round of the FA Cup for just the second time in 20 years.
The visitors took the lead against the run of play through a Famara Diedhiou penalty and despite creating a number of opportunities, Millwall were unable to get the better of Max O'Leary in the Bristol City goal.
The all-Championship encounter was effectively settled by a deflected Nahki Wells free-kick just before the hour mark, before Antoine Semenyo capped a thoroughly professional performance from Dean Holden's side.
Despite their indifferent league form, Millwall were much the better side in the opening exchanges, with the lively Mason Bennett drawing a smart stop from O'Leary early on.
On-loan Tottenham man Troy Parrott was next to go close, swivelling sharply on a cross from Kenneth Zohore and he should have done better from 15 yards.
Just when it seemed Millwall's pressure would finally tell as Ryan Leonard stung O'Leary's palms with a fierce drive, Diedhiou intervened just after the half-hour mark.
The Senegal international latched onto a clever through ball from Zak Vyner and as he knocked it past former City goalkeeper Frank Fielding, he was hauled down.
Referee Tony Harrington had no hesitation in pointing to the penalty spot and Diedhiou converted to notch his sixth goal of the campaign and second in this year's FA Cup.
The response from the home side was strong. Tom Bradshaw saw a header cleared off the line by Tommy Rowe but when Bennett was denied yet again, the Lions must have been thinking it was not going to be their day.
If their showing in the opening half had been somewhat low-key, the Robins upped the ante after the break and went on to dominate proceedings.
Semenyo, who had missed a glorious chance to double the visitors' lead right on the stroke of half-time, belted one into the side-netting early on before a slice of fortune for Wells in the 58th minute put the game beyond doubt.
His 20-yard free-kick took a wicked deflection off Millwall's defensive wall, totally wrong-footing Fielding.
That prompted Lions boss Gary Rowett to make wholesale changes from the bench, but City's grip on the contest was not going to be relinquished – and they were in no mood to respect the occasion of Millwall's 350th game in the world's oldest football competition.
Wells' next contribution was much more deliberate, his defence-splitting pass releasing Semenyo after 72 minutes.
He had plenty to do in dealing with the attentions of two Millwall defenders but kept his composure superbly to slide the ball past Fielding and secure his side a last-16 contest against Premier League Sheffield United.
