Millwall exited the Carabao Cup at the Second Round stage with a 3-1 after extra time defeat at Reading on Tuesday night at the Madejski Stadium.
Leandro Bacuna opened the scoring shortly after the half-hour mark, but Shane Ferguson equalised for The Lions minutes later.
However, in the extra-time period, George Evans and a controversial goal from Sam Smith earned The Royals a slot in Round Three.
Neil Harris made ten changes from Saturday's goalless draw at Bristol City, with Byron Webster the only man left standing. Ryan Tunnicliffe made his Lions debut in the centre of midfield.
Reading enjoyed large amount of possession in the early going without threatening the Millwall goal. Gareth McCleary's free-kick, which was blocked by Tunnicliffe, acted as The Royals' best chance in the opening 15 minutes. Evans struck well over the crossbar five minutes later.
The home side took the lead on 34 minutes. Bacuna found a gap in the Millwall defence and unleashed a shot from just over 20 yards out in the bottom corner of the net.
The Lions nearly levelled two minutes later as Calum Butcher sprung the offside trap, but his effort was well stopped by Anssi Jaakkola in the Reading net. From the resulting corner-kick, however, Millwall got themselves back into the game.
A deep kick was kept in play by Tony Craig and as the ball fell the way of Ferguson, the Northern Irishman curled an effort home via a small deflection.
Ben Thompson sized up an opportunity from distance two minutes before the half-time break, but his effort sailed over the crossbar.
The first attempt of the second-half went the way of The Royals, but Chris Gunter side-footed wide. At the other end, Elliott headed an attempt wide, whilst Tunnicliffe's vicious strike missed the target.
On 58 minutes, another Ferguson delivery was met by Webster, but the defender headed over the crossbar when it seemed easier to score.
A neat passage of passing play nearly nudged Reading back in front on 77 minutes, but Adrian Popa narrowly curled over as the heavy rain fell. Popa had another effort three minutes later, but Tom King saved well after a deflection.
As extra-time loomed, substitutes Aiden O'Brien and Morison broke away and into the Reading penalty area, but the final ball from the Irishman was just behind Morison as an opportunity to shoot opened up.
Jed Wallace became Millwall's first use of the fourth substitution rule with extra-time underway, but it was to be The Royals that would edge themselves in front right on the stroke of half-time of the first-half, as Evans curled past King.
Reading made it 3-1 late on in extra-time through Smith, who guided the ball home over King. Seconds before, referee Breakspear decided to wave play on as Wallace was brought to the ground in a dangerous position for Millwall.
Reading: Jaakkola, Gunter, Evans, McCleary (Clement 46'), Bacuna (Loader 94'), Ilori, Quinn (Barrow 71'), Popa, Andresson (Blackett 90+2'), Rinomhota, Smith. Subs not used: Barrett, East, Legg.
Scorer: Bacuna 34', Evans 105', Smith 116'
Millwall: King, Craig, Thompson, Onyedinma, Ferguson (Wallace 96'), Romeo, Butcher (O'Brien 85'), Webster, Tunnicliffe (Williams 78'), Elliott (Morison 66'), Cooper. Subs not used: Archer, Meredith, Hutchinson.
Scorer: Ferguson 37'
Referee: Charles Breakspear
Attendance: 7,148 (471)